From ca30b335154bec9c0f7f7c25a07182557dbb257d Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Mon, 16 May 2022 12:08:43 -0700
Subject: [PATCH 1/9] Update slice to only prefetch when first block is
 miss/hit-stale

---
 doc/admin-guide/plugins/slice.en.rst          |  6 +-
 .../cache_range_requests.cc                   |  2 +
 plugins/experimental/slice/Config.h           |  2 +
 plugins/experimental/slice/Data.h             |  2 +-
 plugins/experimental/slice/intercept.cc       | 11 ++-
 plugins/experimental/slice/prefetch.cc        |  1 -
 plugins/experimental/slice/slice.cc           |  6 ++
 plugins/experimental/slice/util.cc            | 21 +++--
 .../pluginTest/slice/gold/slice_prefetch.gold | 27 ++++++
 .../pluginTest/slice/slice_prefetch.test.py   | 92 +++++++++++--------
 10 files changed, 117 insertions(+), 53 deletions(-)
 create mode 100644 tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold

diff --git a/doc/admin-guide/plugins/slice.en.rst b/doc/admin-guide/plugins/slice.en.rst
index 5a22bf1d3ee..3582581628f 100644
--- a/doc/admin-guide/plugins/slice.en.rst
+++ b/doc/admin-guide/plugins/slice.en.rst
@@ -129,8 +129,10 @@ The slice plugin supports the following options::
     --prefetch-count=<int> (optional)
         Default is 0
         Prefetches successive 'n' slice block requests in the background
-        and cached. Especially for large objects, prefetching can improve
-        cache miss latency.
+        and caches (with `cache_range_requests` plugin). If the first
+        block is a miss or hit-stale, it will prefetch. Otherwise,
+        prefetching is disabled. Especially for large objects,
+        prefetching can improve cache miss latency.
         -f for short
 
 Examples::
diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 7c3b708b869..48c5a459760 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -370,9 +370,11 @@ handle_client_send_response(TSHttpTxn txnp, txndata *const txn_state)
         DEBUG_LOG("Restoring response header to TS_HTTP_STATUS_PARTIAL_CONTENT.");
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
       }
+
     } else {
       DEBUG_LOG("Ignoring status code %d; txn_state->origin_status=%d", status, txn_state->origin_status);
     }
+
     TSHandleMLocRelease(resp_buf, TS_NULL_MLOC, resp_loc);
   }
 
diff --git a/plugins/experimental/slice/Config.h b/plugins/experimental/slice/Config.h
index 8408ffc2076..d7ef1d23019 100644
--- a/plugins/experimental/slice/Config.h
+++ b/plugins/experimental/slice/Config.h
@@ -49,6 +49,8 @@ struct Config {
   std::string m_skip_header;
   std::string m_crr_ims_header;
 
+  TSCont m_contp{nullptr};
+  bool m_first_block{true};
   // Convert optarg to bytes
   static int64_t bytesFrom(char const *const valstr);
 
diff --git a/plugins/experimental/slice/Data.h b/plugins/experimental/slice/Data.h
index 9cfbb2f7ead..8e654a69bc4 100644
--- a/plugins/experimental/slice/Data.h
+++ b/plugins/experimental/slice/Data.h
@@ -93,7 +93,7 @@ struct Data {
   Stage m_upstream;
   Stage m_dnstream;
 
-  std::unordered_map<int, bool> m_fetchstates;
+  bool m_prefetchable{false};
 
   HdrMgr m_req_hdrmgr;  // manager for server request
   HdrMgr m_resp_hdrmgr; // manager for client response
diff --git a/plugins/experimental/slice/intercept.cc b/plugins/experimental/slice/intercept.cc
index 2b6ef3bdfcd..e3094aebdf9 100644
--- a/plugins/experimental/slice/intercept.cc
+++ b/plugins/experimental/slice/intercept.cc
@@ -50,7 +50,16 @@ intercept_hook(TSCont contp, TSEvent event, void *edata)
   case TS_EVENT_ERROR: {
     abort(contp, data);
   } break;
-
+  case TS_EVENT_HTTP_READ_RESPONSE_HDR: {
+    TSHttpTxn const txnp = static_cast<TSHttpTxn>(edata);
+    int lookupStatus;
+    if (data->m_blocknum == 0 && TS_SUCCESS == TSHttpTxnCacheLookupStatusGet(txnp, &lookupStatus)) {
+      if (lookupStatus == TS_CACHE_LOOKUP_MISS || lookupStatus == TS_CACHE_LOOKUP_HIT_STALE) {
+        data->m_prefetchable = true;
+      }
+    }
+    TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
+  } break;
   default: {
     // data from client -- only the initial header
     if (data->m_dnstream.m_read.isOpen() && edata == data->m_dnstream.m_read.m_vio) {
diff --git a/plugins/experimental/slice/prefetch.cc b/plugins/experimental/slice/prefetch.cc
index 2325db77f4b..8fba88b738a 100644
--- a/plugins/experimental/slice/prefetch.cc
+++ b/plugins/experimental/slice/prefetch.cc
@@ -97,7 +97,6 @@ BgBlockFetch::fetch(Data *const data)
     DEBUG_LOG("Headers\n%s", headerstr.c_str());
   }
 
-  data->m_fetchstates[_blocknum] = true;
   return true;
 }
 
diff --git a/plugins/experimental/slice/slice.cc b/plugins/experimental/slice/slice.cc
index abb1630fc1d..8f1f4096c80 100644
--- a/plugins/experimental/slice/slice.cc
+++ b/plugins/experimental/slice/slice.cc
@@ -180,10 +180,16 @@ read_request(TSHttpTxn txnp, Config *const config)
 
       // Grab the transaction
       TSHttpTxnIntercept(icontp, txnp);
+      config->m_contp       = icontp;
+      config->m_first_block = true;
 
       return true;
     } else {
       DEBUG_LOG("slice passing GET request through to next plugin");
+      if (config->m_prefetchcount > 0 && config->m_first_block) {
+        TSHttpTxnHookAdd(txnp, TS_HTTP_READ_RESPONSE_HDR_HOOK, config->m_contp);
+        config->m_first_block = false;
+      }
     }
   }
 
diff --git a/plugins/experimental/slice/util.cc b/plugins/experimental/slice/util.cc
index 7e4bc1148ec..18b00b65233 100644
--- a/plugins/experimental/slice/util.cc
+++ b/plugins/experimental/slice/util.cc
@@ -112,16 +112,19 @@ request_block(TSCont contp, Data *const data)
   }
 
   // if prefetch config set, schedule next block requests in background
-  for (int i = 0; i < data->m_config->m_prefetchcount; i++) {
-    int nextblocknum = data->m_blocknum + i + 1;
-    if (data->m_req_range.blockIsInside(data->m_config->m_blockbytes, nextblocknum) && !data->m_fetchstates[nextblocknum]) {
-      if (BgBlockFetch::schedule(data, nextblocknum)) {
-        DEBUG_LOG("Background fetch requested");
-      } else {
-        DEBUG_LOG("Background fetch not requested");
+  if (data->m_prefetchable && data->m_config->m_prefetchcount > 0) {
+    int nextblocknum = 2;
+    if (data->m_blocknum > 1) {
+      nextblocknum = data->m_blocknum + data->m_config->m_prefetchcount;
+    }
+    for (int i = nextblocknum; i <= data->m_blocknum + data->m_config->m_prefetchcount; i++) {
+      if (data->m_req_range.blockIsInside(data->m_config->m_blockbytes, i)) {
+        if (BgBlockFetch::schedule(data, i)) {
+          DEBUG_LOG("Background fetch requested");
+        } else {
+          DEBUG_LOG("Background fetch not requested");
+        }
       }
-    } else {
-      break;
     }
   }
   // get ready for data back from the server
diff --git a/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold b/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold
new file mode 100644
index 00000000000..173fac042a6
--- /dev/null
+++ b/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold
@@ -0,0 +1,27 @@
+bytes 0-6/18 miss
+bytes ``/18 miss
+bytes ``/18 miss
+bytes 14-17/18 hit-fresh
+- miss, none
+bytes 0-6/18 hit-fresh
+bytes 7-13/18 hit-fresh
+bytes 14-17/18 hit-fresh
+- hit-fresh, none
+bytes 0-6/18 hit-stale
+bytes ``/18 hit-stale
+bytes ``/18 hit-stale
+bytes 14-17/18 hit-fresh
+- hit-stale, none
+bytes 0-4/18 miss
+bytes ``/18 miss
+bytes ``/18 miss
+bytes 10-14/18 hit-fresh
+bytes ``/18 miss
+bytes 15-17/18 hit-fresh
+bytes 0-17/18 miss, none
+bytes 0-6/18 hit-fresh
+bytes 7-13/18 hit-fresh
+bytes 14-17/18 hit-fresh
+bytes 5-16/18 hit-fresh, none
+bytes 0-6/18 hit-fresh
+*/18 hit-fresh, none
diff --git a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
index 5dc6aed134c..4201d6873ff 100644
--- a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
+++ b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
@@ -15,6 +15,7 @@
 #  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
+import os
 
 Test.Summary = '''
 slice plugin prefetch feature test
@@ -27,6 +28,7 @@
 Test.SkipUnless(
     Condition.PluginExists('slice.so'),
     Condition.PluginExists('cache_range_requests.so'),
+    Condition.PluginExists('xdebug.so'),
 )
 Test.ContinueOnFail = False
 
@@ -52,7 +54,7 @@
 response_header = {"headers":
                    "HTTP/1.1 200 OK\r\n" +
                    "Connection: close\r\n" +
-                   "Cache-Control: public, max-age=500\r\n" +
+                   "Cache-Control: public, max-age=5\r\n" +
                    "\r\n",
                    "timestamp": "1469733493.993",
                    "body": body,
@@ -79,7 +81,7 @@
         resp_header = {"headers":
                        "HTTP/1.1 206 Partial Content\r\n" +
                        "Accept-Ranges: bytes\r\n" +
-                       "Cache-Control: public, max-age=500\r\n" +
+                       "Cache-Control: public, max-age=5\r\n" +
                        f"Content-Range: bytes {b0}-{b1}/{bodylen}\r\n" +
                        "Connection: close\r\n" +
                        "\r\n",
@@ -88,91 +90,103 @@
                        }
         server.addResponse("sessionlog.json", req_header, resp_header)
 
-curl_and_args = 'curl -s -D /dev/stdout -o /dev/stderr -x http://127.0.0.1:{}'.format(ts.Variables.port)
+curl_and_args = 'curl -s -D /dev/stdout -o /dev/stderr -x http://127.0.0.1:{} -H "x-debug: x-cache"'.format(ts.Variables.port)
 
 ts.Disk.remap_config.AddLines([
-    f'map http://sliceprefetch1bytes1/ http://127.0.0.1:{server.Variables.Port}' +
-    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_1} @pparam=--prefetch-count=1' +
+    f'map http://sliceprefetchbytes1/ http://127.0.0.1:{server.Variables.Port}' +
+    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_1} @pparam=--prefetch-count=1 \\' +
     ' @plugin=cache_range_requests.so',
-    f'map http://sliceprefetch2bytes1/ http://127.0.0.1:{server.Variables.Port}' +
-    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_1} @pparam=--prefetch-count=2' +
-    ' @plugin=cache_range_requests.so',
-    f'map http://sliceprefetch1bytes2/ http://127.0.0.1:{server.Variables.Port}' +
-    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_2} @pparam=--prefetch-count=1' +
-    ' @plugin=cache_range_requests.so',
-    f'map http://sliceprefetch2bytes2/ http://127.0.0.1:{server.Variables.Port}' +
-    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_2} @pparam=--prefetch-count=2' +
+    f'map http://sliceprefetchbytes2/ http://127.0.0.1:{server.Variables.Port}' +
+    f' @plugin=slice.so @pparam=--blockbytes-test={block_bytes_2} @pparam=--prefetch-count=3 \\' +
     ' @plugin=cache_range_requests.so',
 ])
 
+ts.Disk.plugin_config.AddLine('xdebug.so')
+ts.Disk.logging_yaml.AddLines([
+    'logging:',
+    '  formats:',
+    '  - name: cache',
+    '    format: "%<{Content-Range}psh> %<{X-Cache}psh>"',
+    '  logs:',
+    '    - filename: cache',
+    '      format: cache',
+    '      mode: ascii',
+])
+
 ts.Disk.records_config.update({
     'proxy.config.diags.debug.enabled': 1,
-    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|pvc',
+    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|xdebug',
 })
 
-# 0 Test - Full object slice with only next block prefetched in background, block bytes= 7
-tr = Test.AddTestRun("Full object slice with only next block prefetched in background, block bytes= 7")
+# 0 Test - Full object slice (miss) with only block 14-20 prefetched in background, block bytes= 7
+tr = Test.AddTestRun("Full object slice: first block is miss, only block 14-20 prefetched")
 ps = tr.Processes.Default
 ps.StartBefore(server, ready=When.PortOpen(server.Variables.Port))
 ps.StartBefore(Test.Processes.ts)
-ps.Command = curl_and_args + ' http://sliceprefetch1bytes1/path'
+ps.Command = curl_and_args + ' http://sliceprefetchbytes1/path'
 ps.ReturnCode = 0
 ps.Streams.stderr = "gold/slice_200.stderr.gold"
 ps.Streams.stdout.Content = Testers.ContainsExpression("200 OK", "expected 200 OK response")
+ps.Streams.stdout.Content += Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
 tr.StillRunningAfter = ts
 
-# 1 Test - Full object slice with nest 2 blocks prefetched in background, block bytes= 7
-tr = Test.AddTestRun("Test - Full object slice with nest 2 blocks prefetched in background, block bytes= 7")
+# 1 Test - Full object slice (hit-fresh) with no prefetched blocks, block bytes= 7
+tr = Test.AddTestRun("Full object slice: first block is hit-fresh, no blocks prefetched")
 ps = tr.Processes.Default
-ps.Command = curl_and_args + ' http://sliceprefetch2bytes1/path'
+ps.Command = 'sleep 1; ' + curl_and_args + ' http://sliceprefetchbytes1/path'
 ps.ReturnCode = 0
 ps.Streams.stderr = "gold/slice_200.stderr.gold"
 ps.Streams.stdout.Content = Testers.ContainsExpression("200 OK", "expected 200 OK response")
+ps.Streams.stdout.Content += Testers.ContainsExpression("X-Cache: hit-fresh", "expected cache fresh")
 tr.StillRunningAfter = ts
 
-# 2 Test - Full object slice with only next block prefetched in background, block bytes= 5
-tr = Test.AddTestRun("Full object slice with only next block prefetched in background, block bytes= 5")
+# 2 Test - Full object slice with only next block prefetched in background, block bytes= 7
+tr = Test.AddTestRun("Full object slice: first block is hit-stale, only block 14-20 prefetched")
 ps = tr.Processes.Default
-ps.Command = curl_and_args + ' http://sliceprefetch1bytes2/path'
+ps.Command = 'sleep 5; ' + curl_and_args + ' http://sliceprefetchbytes1/path'
 ps.ReturnCode = 0
 ps.Streams.stderr = "gold/slice_200.stderr.gold"
 ps.Streams.stdout.Content = Testers.ContainsExpression("200 OK", "expected 200 OK response")
+ps.Streams.stdout.Content += Testers.ContainsExpression("X-Cache: hit-stale", "expected cache hit-stale")
 tr.StillRunningAfter = ts
 
-# 3 Test - Full object slice with nest 2 blocks prefetched in background, block bytes= 5
-tr = Test.AddTestRun("Full object slice with nest 2 blocks prefetched in background, block bytes= 5")
+# 3 Test - Full object slice (miss) with only blocks 10-14, 15-19 prefetched in background, block bytes= 5
+tr = Test.AddTestRun("Full object slice: first block is miss, only blocks 10-14, 15-19 prefetched")
 ps = tr.Processes.Default
-ps.Command = curl_and_args + ' http://sliceprefetch2bytes2/path'
+ps.Command = curl_and_args + ' http://sliceprefetchbytes2/path' + ' -r 0-'
 ps.ReturnCode = 0
 ps.Streams.stderr = "gold/slice_200.stderr.gold"
-ps.Streams.stdout.Content = Testers.ContainsExpression("200 OK", "expected 200 OK response")
-tr.StillRunningAfter = ts
-
-# 4 Test - Whole asset via range
-tr = Test.AddTestRun("Whole asset via range")
-ps = tr.Processes.Default
-ps.Command = curl_and_args + ' http://sliceprefetch1bytes1/path' + ' -r 0-'
-ps.ReturnCode = 0
-ps.Streams.stderr = "gold/slice_206.stderr.gold"
 ps.Streams.stdout.Content = Testers.ContainsExpression("206 Partial Content", "expected 206 response")
 ps.Streams.stdout.Content += Testers.ContainsExpression("Content-Range: bytes 0-17/18", "mismatch byte content response")
+ps.Streams.stdout.Content += Testers.ContainsExpression("X-Cache: miss", "expected cache miss")
 tr.StillRunningAfter = ts
 
-# 5 Test - Non aligned slice request
+# 4 Test - Non aligned slice request
 tr = Test.AddTestRun("Non aligned slice request")
 ps = tr.Processes.Default
-ps.Command = curl_and_args + ' http://sliceprefetch1bytes1/path' + ' -r 5-16'
+ps.Command = curl_and_args + ' http://sliceprefetchbytes1/path' + ' -r 5-16'
 ps.ReturnCode = 0
 ps.Streams.stderr = "gold/slice_mid.stderr.gold"
 ps.Streams.stdout.Content = Testers.ContainsExpression("206 Partial Content", "expected 206 response")
 ps.Streams.stdout.Content += Testers.ContainsExpression("Content-Range: bytes 5-16/18", "mismatch byte content response")
 tr.StillRunningAfter = ts
 
-# 6 Test - special case, begin inside last slice block but outside asset len
+# 5 Test - special case, begin inside last slice block but outside asset len
 tr = Test.AddTestRun("Invalid end range request, 416")
 beg = len(body) + 1
 end = beg + block_bytes
 ps = tr.Processes.Default
-ps.Command = curl_and_args + f' http://sliceprefetch1bytes1/path -r {beg}-{end}'
+ps.Command = curl_and_args + f' http://sliceprefetchbytes1/path -r {beg}-{end}'
 ps.Streams.stdout.Content = Testers.ContainsExpression("416 Requested Range Not Satisfiable", "expected 416 response")
 tr.StillRunningAfter = ts
+
+# 6 Test - All requests (client & slice internal) logs to see background fetches
+cache_file = os.path.join(ts.Variables.LOGDIR, 'cache.log')
+# Wait for log file to appear, then wait one extra second to make sure TS is done writing it.
+test_run = Test.AddTestRun("Checking debug logs for background fetches")
+test_run.Processes.Default.Command = (
+    os.path.join(Test.Variables.AtsTestToolsDir, 'condwait') + ' 60 1 -f ' +
+    cache_file
+)
+ts.Disk.File(cache_file).Content = "gold/slice_prefetch.gold"
+test_run.Processes.Default.ReturnCode = 0

From 40e82c282d8ea04b70c92d055daf47ebbba95a2a Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Fri, 10 Jun 2022 10:00:25 -0700
Subject: [PATCH 2/9] Remove extra line spaces & generalize autest output

---
 plugins/cache_range_requests/cache_range_requests.cc      | 2 --
 .../gold_tests/pluginTest/slice/gold/slice_prefetch.gold  | 8 ++++----
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 48c5a459760..7c3b708b869 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -370,11 +370,9 @@ handle_client_send_response(TSHttpTxn txnp, txndata *const txn_state)
         DEBUG_LOG("Restoring response header to TS_HTTP_STATUS_PARTIAL_CONTENT.");
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
       }
-
     } else {
       DEBUG_LOG("Ignoring status code %d; txn_state->origin_status=%d", status, txn_state->origin_status);
     }
-
     TSHandleMLocRelease(resp_buf, TS_NULL_MLOC, resp_loc);
   }
 
diff --git a/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold b/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold
index 173fac042a6..1a82ca139a3 100644
--- a/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold
+++ b/tests/gold_tests/pluginTest/slice/gold/slice_prefetch.gold
@@ -13,10 +13,10 @@ bytes ``/18 hit-stale
 bytes 14-17/18 hit-fresh
 - hit-stale, none
 bytes 0-4/18 miss
-bytes ``/18 miss
-bytes ``/18 miss
-bytes 10-14/18 hit-fresh
-bytes ``/18 miss
+bytes ``/18 ``
+bytes ``/18 ``
+bytes ``/18 ``
+bytes ``/18 ``
 bytes 15-17/18 hit-fresh
 bytes 0-17/18 miss, none
 bytes 0-6/18 hit-fresh

From 7775be64a854319638e7e095413a20dcfdfabfff Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Mon, 13 Jun 2022 09:00:25 -0700
Subject: [PATCH 3/9] Verify cont is valid

---
 plugins/experimental/slice/slice.cc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/plugins/experimental/slice/slice.cc b/plugins/experimental/slice/slice.cc
index 8f1f4096c80..50b474530ed 100644
--- a/plugins/experimental/slice/slice.cc
+++ b/plugins/experimental/slice/slice.cc
@@ -186,7 +186,7 @@ read_request(TSHttpTxn txnp, Config *const config)
       return true;
     } else {
       DEBUG_LOG("slice passing GET request through to next plugin");
-      if (config->m_prefetchcount > 0 && config->m_first_block) {
+      if (config->m_prefetchcount > 0 && config->m_contp != nullptr && config->m_first_block) {
         TSHttpTxnHookAdd(txnp, TS_HTTP_READ_RESPONSE_HDR_HOOK, config->m_contp);
         config->m_first_block = false;
       }

From 665715fe2c24cbd85e73e8ab1b980652b7f4dc38 Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Thu, 23 Jun 2022 14:14:29 -0700
Subject: [PATCH 4/9] Use xdebug to only prefetch when first block is cacheable
 with miss/hit-stale status

---
 doc/admin-guide/plugins/slice.en.rst          |  9 ++--
 plugins/experimental/slice/Config.h           |  2 -
 plugins/experimental/slice/HttpHeader.cc      | 28 ++++++++++
 plugins/experimental/slice/HttpHeader.h       | 11 ++++
 plugins/experimental/slice/intercept.cc       | 11 +---
 plugins/experimental/slice/prefetch.cc        | 53 ++++++++++++-------
 plugins/experimental/slice/prefetch.h         | 17 ++----
 plugins/experimental/slice/server.cc          |  4 ++
 plugins/experimental/slice/slice.cc           |  6 ---
 .../pluginTest/slice/add_via_hdr.config       | 19 +++++++
 .../pluginTest/slice/slice_prefetch.test.py   |  5 +-
 11 files changed, 111 insertions(+), 54 deletions(-)
 create mode 100644 tests/gold_tests/pluginTest/slice/add_via_hdr.config

diff --git a/doc/admin-guide/plugins/slice.en.rst b/doc/admin-guide/plugins/slice.en.rst
index 3582581628f..d949accbfb9 100644
--- a/doc/admin-guide/plugins/slice.en.rst
+++ b/doc/admin-guide/plugins/slice.en.rst
@@ -129,10 +129,11 @@ The slice plugin supports the following options::
     --prefetch-count=<int> (optional)
         Default is 0
         Prefetches successive 'n' slice block requests in the background
-        and caches (with `cache_range_requests` plugin). If the first
-        block is a miss or hit-stale, it will prefetch. Otherwise,
-        prefetching is disabled. Especially for large objects,
-        prefetching can improve cache miss latency.
+        and caches (with `cache_range_requests` plugin). Prefetching is only
+        enabled when first block is written or updated in the cache, which is
+        a cacheable object with miss or hit-stale status. `xdebug` plugin must
+        be enabled with `Via` header request. Otherwise, prefetching is disabled.
+        Especially for large objects, prefetching can improve cache miss latency.
         -f for short
 
 Examples::
diff --git a/plugins/experimental/slice/Config.h b/plugins/experimental/slice/Config.h
index d7ef1d23019..8408ffc2076 100644
--- a/plugins/experimental/slice/Config.h
+++ b/plugins/experimental/slice/Config.h
@@ -49,8 +49,6 @@ struct Config {
   std::string m_skip_header;
   std::string m_crr_ims_header;
 
-  TSCont m_contp{nullptr};
-  bool m_first_block{true};
   // Convert optarg to bytes
   static int64_t bytesFrom(char const *const valstr);
 
diff --git a/plugins/experimental/slice/HttpHeader.cc b/plugins/experimental/slice/HttpHeader.cc
index d98d112a3f7..4df8c9aac71 100644
--- a/plugins/experimental/slice/HttpHeader.cc
+++ b/plugins/experimental/slice/HttpHeader.cc
@@ -320,6 +320,34 @@ HttpHeader::toString() const
   return res;
 }
 
+bool
+HttpHeader::cacheFilled() const
+{
+  if (!isValid()) {
+    return false;
+  }
+
+  char viastr[8192];
+  int vialen = sizeof(viastr);
+  const char *errptr;
+  const char *cache_fill;
+  int erroffset, ovector[OVECTOR_SIZE], match_count;
+
+  // look for expected Via field
+  bool const hasVia(valueForKey(TS_MIME_FIELD_VIA, TS_MIME_LEN_VIA, viastr, &vialen));
+  if (hasVia) {
+    pcre *m_regex = pcre_compile("\\[(.*?)f(.)(.*?):(.*?)\\]", 0, &errptr, &erroffset, nullptr);
+    if (m_regex != nullptr) {
+      match_count = pcre_exec(m_regex, nullptr, viastr, vialen, 0, PCRE_NOTEMPTY, ovector, OVECTOR_SIZE);
+      if (match_count == 5) {
+        pcre_get_substring(viastr, ovector, match_count, 2, &cache_fill);
+        return (!strcmp(cache_fill, "W") || !strcmp(cache_fill, "U"));
+      }
+    }
+  }
+  return false;
+}
+
 /////// HdrMgr
 
 TSParseResult
diff --git a/plugins/experimental/slice/HttpHeader.h b/plugins/experimental/slice/HttpHeader.h
index 15a1b158ef1..3f9409d85b4 100644
--- a/plugins/experimental/slice/HttpHeader.h
+++ b/plugins/experimental/slice/HttpHeader.h
@@ -36,6 +36,14 @@
 
 #include <string>
 
+#ifdef HAVE_PCRE_PCRE_H
+#include <pcre/pcre.h>
+#else
+#include <pcre.h>
+#endif
+
+#define OVECTOR_SIZE 30
+
 /**
   Designed to be a cheap throwaway struct which allows a
   consumer to make various calls to manipulate headers.
@@ -131,6 +139,9 @@ struct HttpHeader {
   // sets header value as a time_t
   bool setKeyTime(char const *const key, int const keylen, time_t const timeval);
 
+  // read "f cache-fill" status of Via Header
+  bool cacheFilled() const;
+
   /** dump header into provided char buffer
    */
   std::string toString() const;
diff --git a/plugins/experimental/slice/intercept.cc b/plugins/experimental/slice/intercept.cc
index e3094aebdf9..2b6ef3bdfcd 100644
--- a/plugins/experimental/slice/intercept.cc
+++ b/plugins/experimental/slice/intercept.cc
@@ -50,16 +50,7 @@ intercept_hook(TSCont contp, TSEvent event, void *edata)
   case TS_EVENT_ERROR: {
     abort(contp, data);
   } break;
-  case TS_EVENT_HTTP_READ_RESPONSE_HDR: {
-    TSHttpTxn const txnp = static_cast<TSHttpTxn>(edata);
-    int lookupStatus;
-    if (data->m_blocknum == 0 && TS_SUCCESS == TSHttpTxnCacheLookupStatusGet(txnp, &lookupStatus)) {
-      if (lookupStatus == TS_CACHE_LOOKUP_MISS || lookupStatus == TS_CACHE_LOOKUP_HIT_STALE) {
-        data->m_prefetchable = true;
-      }
-    }
-    TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
-  } break;
+
   default: {
     // data from client -- only the initial header
     if (data->m_dnstream.m_read.isOpen() && edata == data->m_dnstream.m_read.m_vio) {
diff --git a/plugins/experimental/slice/prefetch.cc b/plugins/experimental/slice/prefetch.cc
index 8fba88b738a..a83d25a6310 100644
--- a/plugins/experimental/slice/prefetch.cc
+++ b/plugins/experimental/slice/prefetch.cc
@@ -43,13 +43,13 @@ BgBlockFetch::schedule(Data *const data, int blocknum)
 bool
 BgBlockFetch::fetch(Data *const data)
 {
-  if (_bg_stream.m_read.isOpen()) {
+  if (m_stream.m_read.isOpen()) {
     // should never happen since the connection was just initialized
     ERROR_LOG("Background block request already in flight!");
     return false;
   }
 
-  int64_t const blockbeg = (data->m_config->m_blockbytes * _blocknum);
+  int64_t const blockbeg = (data->m_config->m_blockbytes * m_blocknum);
   Range blockbe(blockbeg, blockbeg + data->m_config->m_blockbytes);
 
   char rangestr[1024];
@@ -69,11 +69,11 @@ BgBlockFetch::fetch(Data *const data)
     ERROR_LOG("Error trying to set range request header %s", rangestr);
     return false;
   }
-  TSAssert(nullptr == _cont);
+  TSAssert(nullptr == m_cont);
 
   // Setup the continuation
-  _cont = TSContCreate(handler, TSMutexCreate());
-  TSContDataSet(_cont, static_cast<void *>(this));
+  m_cont = TSContCreate(handler, TSMutexCreate());
+  TSContDataSet(m_cont, static_cast<void *>(this));
 
   // create virtual connection back into ATS
   TSHttpConnectOptions options = TSHttpConnectOptionsGet(TS_CONNECT_PLUGIN);
@@ -88,14 +88,16 @@ BgBlockFetch::fetch(Data *const data)
   int const hlen = TSHttpHdrLengthGet(header.m_buffer, header.m_lochdr);
 
   // set up connection with the HttpConnect server
-  _bg_stream.setupConnection(upvc);
-  _bg_stream.setupVioWrite(_cont, hlen);
-  TSHttpHdrPrint(header.m_buffer, header.m_lochdr, _bg_stream.m_write.m_iobuf);
+  m_stream.setupConnection(upvc);
+  m_stream.setupVioWrite(m_cont, hlen);
+  TSHttpHdrPrint(header.m_buffer, header.m_lochdr, m_stream.m_write.m_iobuf);
 
   if (TSIsDebugTagSet(PLUGIN_NAME)) {
     std::string const headerstr(header.toString());
     DEBUG_LOG("Headers\n%s", headerstr.c_str());
   }
+  // ensure blocks are pulled through to cache
+  m_stream.setupVioRead(m_cont, INT64_MAX);
 
   return true;
 }
@@ -112,22 +114,37 @@ BgBlockFetch::handler(TSCont contp, TSEvent event, void * /* edata ATS_UNUSED */
 
   switch (event) {
   case TS_EVENT_VCONN_WRITE_COMPLETE:
-    TSVConnShutdown(bg->_bg_stream.m_vc, 0, 1);
-    bg->_bg_stream.close();
-    delete bg;
+    TSVConnShutdown(bg->m_stream.m_vc, 0, 1);
     break;
-  default:
-    if (event == TS_EVENT_VCONN_INACTIVITY_TIMEOUT) {
-      DEBUG_LOG("encountered Inactivity Timeout");
-      TSVConnAbort(bg->_bg_stream.m_vc, TS_VC_CLOSE_ABORT);
-    } else {
-      TSVConnClose(bg->_bg_stream.m_vc);
+  case TS_EVENT_VCONN_READ_READY: {
+    TSIOBufferReader const reader = bg->m_stream.m_read.m_reader;
+    if (nullptr != reader) {
+      int64_t const avail = TSIOBufferReaderAvail(reader);
+      TSIOBufferReaderConsume(reader, avail);
+      TSVIO const rvio = bg->m_stream.m_read.m_vio;
+      TSVIONDoneSet(rvio, TSVIONDoneGet(rvio) + avail);
+      TSVIOReenable(rvio);
     }
-    bg->_bg_stream.abort();
+  } break;
+  case TS_EVENT_NET_ACCEPT_FAILED:
+  case TS_EVENT_VCONN_INACTIVITY_TIMEOUT:
+  case TS_EVENT_VCONN_ACTIVE_TIMEOUT:
+  case TS_EVENT_ERROR:
+    bg->m_stream.abort();
+    TSContDataSet(contp, nullptr);
+    delete bg;
+    TSContDestroy(contp);
+    break;
+  case TS_EVENT_VCONN_READ_COMPLETE:
+  case TS_EVENT_VCONN_EOS:
+    bg->m_stream.close();
     TSContDataSet(contp, nullptr);
     delete bg;
     TSContDestroy(contp);
     break;
+  default:
+    DEBUG_LOG("Unhandled bg fetch event:%s (%d)", TSHttpEventNameLookup(event), event);
+    break;
   }
   return 0;
 }
diff --git a/plugins/experimental/slice/prefetch.h b/plugins/experimental/slice/prefetch.h
index e04376bacf6..e5d1edfc247 100644
--- a/plugins/experimental/slice/prefetch.h
+++ b/plugins/experimental/slice/prefetch.h
@@ -35,22 +35,13 @@
 struct BgBlockFetch {
   static bool schedule(Data *const data, int blocknum);
 
-  explicit BgBlockFetch(int blocknum) : _blocknum(blocknum) {}
+  explicit BgBlockFetch(int blocknum) : m_blocknum(blocknum) {}
 
   bool fetch(Data *const data);
   static int handler(TSCont contp, TSEvent event, void * /* edata ATS_UNUSED */);
 
   /* This is for the actual background fetch / NetVC */
-  Stage _bg_stream;
-
-  int _blocknum;
-  TSCont _cont = nullptr;
-
-  ~BgBlockFetch()
-  {
-    if (nullptr != _cont) {
-      TSContDestroy(_cont);
-      _cont = nullptr;
-    }
-  }
+  Stage m_stream;
+  int m_blocknum;
+  TSCont m_cont = nullptr;
 };
\ No newline at end of file
diff --git a/plugins/experimental/slice/server.cc b/plugins/experimental/slice/server.cc
index ddf0cc9ad2f..40172b77732 100644
--- a/plugins/experimental/slice/server.cc
+++ b/plugins/experimental/slice/server.cc
@@ -217,6 +217,10 @@ handleFirstServerHeader(Data *const data, TSCont const contp)
   data->m_bytessent = hbytes;
   TSVIOReenable(output_vio);
 
+  if (data->m_config->m_prefetchcount > 0 && header.cacheFilled()) {
+    data->m_prefetchable = true;
+  }
+
   return HeaderState::Good;
 }
 
diff --git a/plugins/experimental/slice/slice.cc b/plugins/experimental/slice/slice.cc
index 50b474530ed..abb1630fc1d 100644
--- a/plugins/experimental/slice/slice.cc
+++ b/plugins/experimental/slice/slice.cc
@@ -180,16 +180,10 @@ read_request(TSHttpTxn txnp, Config *const config)
 
       // Grab the transaction
       TSHttpTxnIntercept(icontp, txnp);
-      config->m_contp       = icontp;
-      config->m_first_block = true;
 
       return true;
     } else {
       DEBUG_LOG("slice passing GET request through to next plugin");
-      if (config->m_prefetchcount > 0 && config->m_contp != nullptr && config->m_first_block) {
-        TSHttpTxnHookAdd(txnp, TS_HTTP_READ_RESPONSE_HDR_HOOK, config->m_contp);
-        config->m_first_block = false;
-      }
     }
   }
 
diff --git a/tests/gold_tests/pluginTest/slice/add_via_hdr.config b/tests/gold_tests/pluginTest/slice/add_via_hdr.config
new file mode 100644
index 00000000000..2dee8ec1f5d
--- /dev/null
+++ b/tests/gold_tests/pluginTest/slice/add_via_hdr.config
@@ -0,0 +1,19 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+cond %{READ_REQUEST_HDR_HOOK}
+    add-header X-Debug Via
\ No newline at end of file
diff --git a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
index 4201d6873ff..c5a5aa2fd8e 100644
--- a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
+++ b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
@@ -29,6 +29,7 @@
     Condition.PluginExists('slice.so'),
     Condition.PluginExists('cache_range_requests.so'),
     Condition.PluginExists('xdebug.so'),
+    Condition.PluginExists('header_rewrite.so'),
 )
 Test.ContinueOnFail = False
 
@@ -101,7 +102,9 @@
     ' @plugin=cache_range_requests.so',
 ])
 
+ts.Setup.CopyAs('add_via_hdr.config', Test.RunDirectory)
 ts.Disk.plugin_config.AddLine('xdebug.so')
+ts.Disk.plugin_config.AddLine(f'header_rewrite.so {Test.RunDirectory}/add_via_hdr.config')
 ts.Disk.logging_yaml.AddLines([
     'logging:',
     '  formats:',
@@ -115,7 +118,7 @@
 
 ts.Disk.records_config.update({
     'proxy.config.diags.debug.enabled': 1,
-    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|xdebug',
+    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|xdebug|header_rewrite',
 })
 
 # 0 Test - Full object slice (miss) with only block 14-20 prefetched in background, block bytes= 7

From c6c57a2e646a224aa7fae4250e7837a9dc59b22b Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Mon, 18 Jul 2022 12:26:39 -0700
Subject: [PATCH 5/9] Precompile via regex pattern in config

---
 plugins/experimental/slice/Config.cc     |  6 ++++++
 plugins/experimental/slice/Config.h      |  1 +
 plugins/experimental/slice/HttpHeader.cc | 10 ++++------
 plugins/experimental/slice/HttpHeader.h  |  2 +-
 plugins/experimental/slice/server.cc     |  2 +-
 5 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/plugins/experimental/slice/Config.cc b/plugins/experimental/slice/Config.cc
index 5cd71d47339..13638cba870 100644
--- a/plugins/experimental/slice/Config.cc
+++ b/plugins/experimental/slice/Config.cc
@@ -44,6 +44,9 @@ Config::~Config()
   if (nullptr != m_regex) {
     pcre_free(m_regex);
   }
+  if (nullptr != m_via_regex) {
+    pcre_free(m_via_regex);
+  }
 }
 
 int64_t
@@ -224,6 +227,9 @@ Config::fromArgs(int const argc, char const *const argv[])
       }
     } break;
     case 'f': {
+      const char *errptr;
+      int erroffset;
+      m_via_regex     = pcre_compile("\\[(.*?)f(.)(.*?):(.*?)\\]", 0, &errptr, &erroffset, nullptr);
       m_prefetchcount = atoi(optarg);
     } break;
     default:
diff --git a/plugins/experimental/slice/Config.h b/plugins/experimental/slice/Config.h
index 8408ffc2076..7cae95baadf 100644
--- a/plugins/experimental/slice/Config.h
+++ b/plugins/experimental/slice/Config.h
@@ -40,6 +40,7 @@ struct Config {
   enum RegexType { None, Include, Exclude };
   RegexType m_regex_type{None};
   pcre *m_regex{nullptr};
+  pcre *m_via_regex{nullptr};
   pcre_extra *m_regex_extra{nullptr};
   int m_paceerrsecs{0};   // -1 disable logging, 0 no pacing, max 60s
   int m_prefetchcount{0}; // 0 disables prefetching
diff --git a/plugins/experimental/slice/HttpHeader.cc b/plugins/experimental/slice/HttpHeader.cc
index 4df8c9aac71..c5c3c344143 100644
--- a/plugins/experimental/slice/HttpHeader.cc
+++ b/plugins/experimental/slice/HttpHeader.cc
@@ -321,7 +321,7 @@ HttpHeader::toString() const
 }
 
 bool
-HttpHeader::cacheFilled() const
+HttpHeader::cacheFilled(pcre *regex_pat) const
 {
   if (!isValid()) {
     return false;
@@ -329,16 +329,14 @@ HttpHeader::cacheFilled() const
 
   char viastr[8192];
   int vialen = sizeof(viastr);
-  const char *errptr;
   const char *cache_fill;
-  int erroffset, ovector[OVECTOR_SIZE], match_count;
+  int ovector[OVECTOR_SIZE], match_count;
 
   // look for expected Via field
   bool const hasVia(valueForKey(TS_MIME_FIELD_VIA, TS_MIME_LEN_VIA, viastr, &vialen));
   if (hasVia) {
-    pcre *m_regex = pcre_compile("\\[(.*?)f(.)(.*?):(.*?)\\]", 0, &errptr, &erroffset, nullptr);
-    if (m_regex != nullptr) {
-      match_count = pcre_exec(m_regex, nullptr, viastr, vialen, 0, PCRE_NOTEMPTY, ovector, OVECTOR_SIZE);
+    if (regex_pat != nullptr) {
+      match_count = pcre_exec(regex_pat, nullptr, viastr, vialen, 0, PCRE_NOTEMPTY, ovector, OVECTOR_SIZE);
       if (match_count == 5) {
         pcre_get_substring(viastr, ovector, match_count, 2, &cache_fill);
         return (!strcmp(cache_fill, "W") || !strcmp(cache_fill, "U"));
diff --git a/plugins/experimental/slice/HttpHeader.h b/plugins/experimental/slice/HttpHeader.h
index 3f9409d85b4..0c2348f4cb7 100644
--- a/plugins/experimental/slice/HttpHeader.h
+++ b/plugins/experimental/slice/HttpHeader.h
@@ -140,7 +140,7 @@ struct HttpHeader {
   bool setKeyTime(char const *const key, int const keylen, time_t const timeval);
 
   // read "f cache-fill" status of Via Header
-  bool cacheFilled() const;
+  bool cacheFilled(pcre *regex_pat) const;
 
   /** dump header into provided char buffer
    */
diff --git a/plugins/experimental/slice/server.cc b/plugins/experimental/slice/server.cc
index 40172b77732..de1ff4f6a9f 100644
--- a/plugins/experimental/slice/server.cc
+++ b/plugins/experimental/slice/server.cc
@@ -217,7 +217,7 @@ handleFirstServerHeader(Data *const data, TSCont const contp)
   data->m_bytessent = hbytes;
   TSVIOReenable(output_vio);
 
-  if (data->m_config->m_prefetchcount > 0 && header.cacheFilled()) {
+  if (data->m_config->m_prefetchcount > 0 && header.cacheFilled(data->m_config->m_via_regex)) {
     data->m_prefetchable = true;
   }
 

From afb7e7ee33dcff7a22441743e04207feef7ffe7f Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Fri, 22 Jul 2022 10:57:08 -0700
Subject: [PATCH 6/9] Remove plugin dependency, add cache status header between
 slice and crr

---
 doc/admin-guide/plugins/slice.en.rst          |  4 +--
 .../cache_range_requests.cc                   | 24 +++++++++++++++++
 plugins/experimental/slice/Config.cc          |  6 -----
 plugins/experimental/slice/Config.h           |  1 -
 plugins/experimental/slice/HttpHeader.cc      | 26 -------------------
 plugins/experimental/slice/HttpHeader.h       | 11 +-------
 plugins/experimental/slice/server.cc          |  3 ++-
 plugins/experimental/slice/util.cc            |  7 +++++
 .../pluginTest/slice/add_via_hdr.config       | 19 --------------
 .../pluginTest/slice/slice_prefetch.test.py   |  5 +---
 10 files changed, 36 insertions(+), 70 deletions(-)
 delete mode 100644 tests/gold_tests/pluginTest/slice/add_via_hdr.config

diff --git a/doc/admin-guide/plugins/slice.en.rst b/doc/admin-guide/plugins/slice.en.rst
index d949accbfb9..f9f26bdf3fe 100644
--- a/doc/admin-guide/plugins/slice.en.rst
+++ b/doc/admin-guide/plugins/slice.en.rst
@@ -130,9 +130,7 @@ The slice plugin supports the following options::
         Default is 0
         Prefetches successive 'n' slice block requests in the background
         and caches (with `cache_range_requests` plugin). Prefetching is only
-        enabled when first block is written or updated in the cache, which is
-        a cacheable object with miss or hit-stale status. `xdebug` plugin must
-        be enabled with `Via` header request. Otherwise, prefetching is disabled.
+        enabled when first block is a cacheable object with miss or hit-stale status.
         Especially for large objects, prefetching can improve cache miss latency.
         -f for short
 
diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 7c3b708b869..83bc4e9a417 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -48,6 +48,7 @@ using parent_select_mode_t = enum parent_select_mode {
 };
 
 constexpr std::string_view DefaultImsHeader = {"X-Crr-Ims"};
+static char const *const SLICE_CRR_HEADER   = {"Slice-Crr-Status"};
 
 struct pluginconfig {
   parent_select_mode_t ps_mode{PS_DEFAULT};
@@ -64,6 +65,8 @@ struct txndata {
   time_t ims_time{0};
   bool verify_cacheability{false};
   bool cache_complete_responses{false};
+  bool slice_response{false};
+  bool slice_request{false};
 };
 
 // pluginconfig struct (global plugin only)
@@ -296,6 +299,13 @@ range_header_check(TSHttpTxn txnp, pluginconfig *const pc)
           TSHttpTxnHookAdd(txnp, TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK, txn_contp);
           DEBUG_LOG("Also Added TS_HTTP_CACHE_LOOKUP_COMPLETE_HOOK");
         }
+
+        // check if slice requests for cache lookup status
+        TSMLoc const locfield(TSMimeHdrFieldFind(hdr_buf, hdr_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER)));
+        if (nullptr != locfield) {
+          TSHandleMLocRelease(hdr_buf, hdr_loc, locfield);
+          txn_state->slice_request = true;
+        }
       }
       TSHandleMLocRelease(hdr_buf, hdr_loc, range_loc);
     } else {
@@ -370,6 +380,12 @@ handle_client_send_response(TSHttpTxn txnp, txndata *const txn_state)
         DEBUG_LOG("Restoring response header to TS_HTTP_STATUS_PARTIAL_CONTENT.");
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
       }
+
+      remove_header(resp_buf, resp_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER));
+      if (txn_state->slice_response) {
+        std::string valStr = "-";
+        set_header(resp_buf, resp_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER), valStr.c_str(), valStr.length());
+      }
     } else {
       DEBUG_LOG("Ignoring status code %d; txn_state->origin_status=%d", status, txn_state->origin_status);
     }
@@ -404,6 +420,7 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
 {
   TSMBuffer resp_buf = nullptr;
   TSMLoc resp_loc    = TS_NULL_MLOC;
+  int cache_lookup;
 
   if (TS_SUCCESS == TSHttpTxnServerRespGet(txnp, &resp_buf, &resp_loc)) {
     TSHttpStatus const status = TSHttpHdrStatusGet(resp_buf, resp_loc);
@@ -433,6 +450,13 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
         DEBUG_LOG("Allowing object to be cached.");
       }
     }
+    // slice requesting cache lookup status and cacheability
+    if (txn_state->slice_request && TSHttpTxnIsCacheable(txnp, nullptr, resp_buf) &&
+        TSHttpTxnCacheLookupStatusGet(txnp, &cache_lookup) == TS_SUCCESS &&
+        (cache_lookup == TS_CACHE_LOOKUP_MISS || cache_lookup == TS_CACHE_LOOKUP_HIT_STALE)) {
+      txn_state->slice_response = true;
+    }
+
     TSHandleMLocRelease(resp_buf, TS_NULL_MLOC, resp_loc);
   }
 }
diff --git a/plugins/experimental/slice/Config.cc b/plugins/experimental/slice/Config.cc
index 13638cba870..5cd71d47339 100644
--- a/plugins/experimental/slice/Config.cc
+++ b/plugins/experimental/slice/Config.cc
@@ -44,9 +44,6 @@ Config::~Config()
   if (nullptr != m_regex) {
     pcre_free(m_regex);
   }
-  if (nullptr != m_via_regex) {
-    pcre_free(m_via_regex);
-  }
 }
 
 int64_t
@@ -227,9 +224,6 @@ Config::fromArgs(int const argc, char const *const argv[])
       }
     } break;
     case 'f': {
-      const char *errptr;
-      int erroffset;
-      m_via_regex     = pcre_compile("\\[(.*?)f(.)(.*?):(.*?)\\]", 0, &errptr, &erroffset, nullptr);
       m_prefetchcount = atoi(optarg);
     } break;
     default:
diff --git a/plugins/experimental/slice/Config.h b/plugins/experimental/slice/Config.h
index 7cae95baadf..8408ffc2076 100644
--- a/plugins/experimental/slice/Config.h
+++ b/plugins/experimental/slice/Config.h
@@ -40,7 +40,6 @@ struct Config {
   enum RegexType { None, Include, Exclude };
   RegexType m_regex_type{None};
   pcre *m_regex{nullptr};
-  pcre *m_via_regex{nullptr};
   pcre_extra *m_regex_extra{nullptr};
   int m_paceerrsecs{0};   // -1 disable logging, 0 no pacing, max 60s
   int m_prefetchcount{0}; // 0 disables prefetching
diff --git a/plugins/experimental/slice/HttpHeader.cc b/plugins/experimental/slice/HttpHeader.cc
index c5c3c344143..d98d112a3f7 100644
--- a/plugins/experimental/slice/HttpHeader.cc
+++ b/plugins/experimental/slice/HttpHeader.cc
@@ -320,32 +320,6 @@ HttpHeader::toString() const
   return res;
 }
 
-bool
-HttpHeader::cacheFilled(pcre *regex_pat) const
-{
-  if (!isValid()) {
-    return false;
-  }
-
-  char viastr[8192];
-  int vialen = sizeof(viastr);
-  const char *cache_fill;
-  int ovector[OVECTOR_SIZE], match_count;
-
-  // look for expected Via field
-  bool const hasVia(valueForKey(TS_MIME_FIELD_VIA, TS_MIME_LEN_VIA, viastr, &vialen));
-  if (hasVia) {
-    if (regex_pat != nullptr) {
-      match_count = pcre_exec(regex_pat, nullptr, viastr, vialen, 0, PCRE_NOTEMPTY, ovector, OVECTOR_SIZE);
-      if (match_count == 5) {
-        pcre_get_substring(viastr, ovector, match_count, 2, &cache_fill);
-        return (!strcmp(cache_fill, "W") || !strcmp(cache_fill, "U"));
-      }
-    }
-  }
-  return false;
-}
-
 /////// HdrMgr
 
 TSParseResult
diff --git a/plugins/experimental/slice/HttpHeader.h b/plugins/experimental/slice/HttpHeader.h
index 0c2348f4cb7..f3b23b0851d 100644
--- a/plugins/experimental/slice/HttpHeader.h
+++ b/plugins/experimental/slice/HttpHeader.h
@@ -36,13 +36,7 @@
 
 #include <string>
 
-#ifdef HAVE_PCRE_PCRE_H
-#include <pcre/pcre.h>
-#else
-#include <pcre.h>
-#endif
-
-#define OVECTOR_SIZE 30
+static char const *const SLICE_CRR_HEADER = {"Slice-Crr-Status"};
 
 /**
   Designed to be a cheap throwaway struct which allows a
@@ -139,9 +133,6 @@ struct HttpHeader {
   // sets header value as a time_t
   bool setKeyTime(char const *const key, int const keylen, time_t const timeval);
 
-  // read "f cache-fill" status of Via Header
-  bool cacheFilled(pcre *regex_pat) const;
-
   /** dump header into provided char buffer
    */
   std::string toString() const;
diff --git a/plugins/experimental/slice/server.cc b/plugins/experimental/slice/server.cc
index de1ff4f6a9f..fa56f3aeb3c 100644
--- a/plugins/experimental/slice/server.cc
+++ b/plugins/experimental/slice/server.cc
@@ -20,6 +20,7 @@
 
 #include "Config.h"
 #include "ContentRange.h"
+#include "HttpHeader.h"
 #include "response.h"
 #include "transfer.h"
 #include "util.h"
@@ -217,7 +218,7 @@ handleFirstServerHeader(Data *const data, TSCont const contp)
   data->m_bytessent = hbytes;
   TSVIOReenable(output_vio);
 
-  if (data->m_config->m_prefetchcount > 0 && header.cacheFilled(data->m_config->m_via_regex)) {
+  if (data->m_config->m_prefetchcount > 0 && header.hasKey(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER))) {
     data->m_prefetchable = true;
   }
 
diff --git a/plugins/experimental/slice/util.cc b/plugins/experimental/slice/util.cc
index 18b00b65233..97183716863 100644
--- a/plugins/experimental/slice/util.cc
+++ b/plugins/experimental/slice/util.cc
@@ -18,6 +18,7 @@
 
 #include "util.h"
 #include "prefetch.h"
+#include "HttpHeader.h"
 
 #include "Config.h"
 #include "Data.h"
@@ -86,6 +87,12 @@ request_block(TSCont contp, Data *const data)
     return false;
   }
 
+  header.removeKey(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER));
+  if (data->m_blocknum == 0 && data->m_config->m_prefetchcount > 0) {
+    std::string valStr = "-";
+    header.setKeyVal(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER), valStr.c_str(), valStr.length());
+  }
+
   // create virtual connection back into ATS
   TSHttpConnectOptions options = TSHttpConnectOptionsGet(TS_CONNECT_PLUGIN);
   options.addr                 = reinterpret_cast<sockaddr *>(&data->m_client_ip);
diff --git a/tests/gold_tests/pluginTest/slice/add_via_hdr.config b/tests/gold_tests/pluginTest/slice/add_via_hdr.config
deleted file mode 100644
index 2dee8ec1f5d..00000000000
--- a/tests/gold_tests/pluginTest/slice/add_via_hdr.config
+++ /dev/null
@@ -1,19 +0,0 @@
-#
-# Licensed to the Apache Software Foundation (ASF) under one
-# or more contributor license agreements.  See the NOTICE file
-# distributed with this work for additional information
-# regarding copyright ownership.  The ASF licenses this file
-# to you under the Apache License, Version 2.0 (the
-# "License"); you may not use this file except in compliance
-# with the License.  You may obtain a copy of the License at
-#
-#      http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-cond %{READ_REQUEST_HDR_HOOK}
-    add-header X-Debug Via
\ No newline at end of file
diff --git a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
index c5a5aa2fd8e..4201d6873ff 100644
--- a/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
+++ b/tests/gold_tests/pluginTest/slice/slice_prefetch.test.py
@@ -29,7 +29,6 @@
     Condition.PluginExists('slice.so'),
     Condition.PluginExists('cache_range_requests.so'),
     Condition.PluginExists('xdebug.so'),
-    Condition.PluginExists('header_rewrite.so'),
 )
 Test.ContinueOnFail = False
 
@@ -102,9 +101,7 @@
     ' @plugin=cache_range_requests.so',
 ])
 
-ts.Setup.CopyAs('add_via_hdr.config', Test.RunDirectory)
 ts.Disk.plugin_config.AddLine('xdebug.so')
-ts.Disk.plugin_config.AddLine(f'header_rewrite.so {Test.RunDirectory}/add_via_hdr.config')
 ts.Disk.logging_yaml.AddLines([
     'logging:',
     '  formats:',
@@ -118,7 +115,7 @@
 
 ts.Disk.records_config.update({
     'proxy.config.diags.debug.enabled': 1,
-    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|xdebug|header_rewrite',
+    'proxy.config.diags.debug.tags': 'slice|cache_range_requests|xdebug',
 })
 
 # 0 Test - Full object slice (miss) with only block 14-20 prefetched in background, block bytes= 7

From 1c4ec97195c032569472035ada6c359320071c03 Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Mon, 25 Jul 2022 12:33:49 -0700
Subject: [PATCH 7/9] Only enable prefetching from CRR on 206 partial case from
 origin

---
 plugins/cache_range_requests/cache_range_requests.cc | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 83bc4e9a417..df53ce0a3d2 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -434,7 +434,13 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
       if (txn_state->verify_cacheability && !TSHttpTxnIsCacheable(txnp, nullptr, resp_buf)) {
         DEBUG_LOG("transaction is not cacheable; resetting status code to 206");
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
+      } else if (txn_state->slice_request && TSHttpTxnIsCacheable(txnp, nullptr, resp_buf) &&
+                 TSHttpTxnCacheLookupStatusGet(txnp, &cache_lookup) == TS_SUCCESS &&
+                 (cache_lookup == TS_CACHE_LOOKUP_MISS || cache_lookup == TS_CACHE_LOOKUP_HIT_STALE)) {
+        // slice requesting cache lookup status and cacheability
+        txn_state->slice_response = true;
       }
+
     } else if (TS_HTTP_STATUS_OK == status) {
       bool cacheable = txn_state->cache_complete_responses;
 
@@ -450,12 +456,6 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
         DEBUG_LOG("Allowing object to be cached.");
       }
     }
-    // slice requesting cache lookup status and cacheability
-    if (txn_state->slice_request && TSHttpTxnIsCacheable(txnp, nullptr, resp_buf) &&
-        TSHttpTxnCacheLookupStatusGet(txnp, &cache_lookup) == TS_SUCCESS &&
-        (cache_lookup == TS_CACHE_LOOKUP_MISS || cache_lookup == TS_CACHE_LOOKUP_HIT_STALE)) {
-      txn_state->slice_response = true;
-    }
 
     TSHandleMLocRelease(resp_buf, TS_NULL_MLOC, resp_loc);
   }

From 27a933be4566b405bcc962554eb94bb699ae1284 Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Tue, 26 Jul 2022 11:47:22 -0700
Subject: [PATCH 8/9] Update header type, fix 206 case for 304 in CRR, allow
 header to be used for debugging

---
 .../cache_range_requests.cc                   | 24 ++++++++++---------
 plugins/experimental/slice/HttpHeader.h       |  2 +-
 plugins/experimental/slice/server.cc          |  2 +-
 plugins/experimental/slice/util.cc            |  6 ++---
 4 files changed, 18 insertions(+), 16 deletions(-)

diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index df53ce0a3d2..36b81c6f4ec 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -48,7 +48,7 @@ using parent_select_mode_t = enum parent_select_mode {
 };
 
 constexpr std::string_view DefaultImsHeader = {"X-Crr-Ims"};
-static char const *const SLICE_CRR_HEADER   = {"Slice-Crr-Status"};
+constexpr std::string_view SLICE_CRR_HEADER = {"Slice-Crr-Status"};
 
 struct pluginconfig {
   parent_select_mode_t ps_mode{PS_DEFAULT};
@@ -301,7 +301,7 @@ range_header_check(TSHttpTxn txnp, pluginconfig *const pc)
         }
 
         // check if slice requests for cache lookup status
-        TSMLoc const locfield(TSMimeHdrFieldFind(hdr_buf, hdr_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER)));
+        TSMLoc const locfield(TSMimeHdrFieldFind(hdr_buf, hdr_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size()));
         if (nullptr != locfield) {
           TSHandleMLocRelease(hdr_buf, hdr_loc, locfield);
           txn_state->slice_request = true;
@@ -381,10 +381,10 @@ handle_client_send_response(TSHttpTxn txnp, txndata *const txn_state)
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
       }
 
-      remove_header(resp_buf, resp_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER));
+      remove_header(resp_buf, resp_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size());
       if (txn_state->slice_response) {
-        std::string valStr = "-";
-        set_header(resp_buf, resp_loc, SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER), valStr.c_str(), valStr.length());
+        std::string valStr = "1";
+        set_header(resp_buf, resp_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), valStr.c_str(), valStr.length());
       }
     } else {
       DEBUG_LOG("Ignoring status code %d; txn_state->origin_status=%d", status, txn_state->origin_status);
@@ -434,13 +434,7 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
       if (txn_state->verify_cacheability && !TSHttpTxnIsCacheable(txnp, nullptr, resp_buf)) {
         DEBUG_LOG("transaction is not cacheable; resetting status code to 206");
         TSHttpHdrStatusSet(resp_buf, resp_loc, TS_HTTP_STATUS_PARTIAL_CONTENT);
-      } else if (txn_state->slice_request && TSHttpTxnIsCacheable(txnp, nullptr, resp_buf) &&
-                 TSHttpTxnCacheLookupStatusGet(txnp, &cache_lookup) == TS_SUCCESS &&
-                 (cache_lookup == TS_CACHE_LOOKUP_MISS || cache_lookup == TS_CACHE_LOOKUP_HIT_STALE)) {
-        // slice requesting cache lookup status and cacheability
-        txn_state->slice_response = true;
       }
-
     } else if (TS_HTTP_STATUS_OK == status) {
       bool cacheable = txn_state->cache_complete_responses;
 
@@ -457,6 +451,14 @@ handle_server_read_response(TSHttpTxn txnp, txndata *const txn_state)
       }
     }
 
+    // slice requesting cache lookup status and cacheability (only on miss or validation)
+    if ((txn_state->origin_status == TS_HTTP_STATUS_PARTIAL_CONTENT || txn_state->origin_status == TS_HTTP_STATUS_NOT_MODIFIED) &&
+        txn_state->slice_request && TSHttpTxnIsCacheable(txnp, nullptr, resp_buf) &&
+        TSHttpTxnCacheLookupStatusGet(txnp, &cache_lookup) == TS_SUCCESS &&
+        (cache_lookup == TS_CACHE_LOOKUP_MISS || cache_lookup == TS_CACHE_LOOKUP_HIT_STALE)) {
+      txn_state->slice_response = true;
+    }
+
     TSHandleMLocRelease(resp_buf, TS_NULL_MLOC, resp_loc);
   }
 }
diff --git a/plugins/experimental/slice/HttpHeader.h b/plugins/experimental/slice/HttpHeader.h
index f3b23b0851d..9c4be14d760 100644
--- a/plugins/experimental/slice/HttpHeader.h
+++ b/plugins/experimental/slice/HttpHeader.h
@@ -36,7 +36,7 @@
 
 #include <string>
 
-static char const *const SLICE_CRR_HEADER = {"Slice-Crr-Status"};
+constexpr std::string_view SLICE_CRR_HEADER = {"Slice-Crr-Status"};
 
 /**
   Designed to be a cheap throwaway struct which allows a
diff --git a/plugins/experimental/slice/server.cc b/plugins/experimental/slice/server.cc
index fa56f3aeb3c..a25376bc920 100644
--- a/plugins/experimental/slice/server.cc
+++ b/plugins/experimental/slice/server.cc
@@ -218,7 +218,7 @@ handleFirstServerHeader(Data *const data, TSCont const contp)
   data->m_bytessent = hbytes;
   TSVIOReenable(output_vio);
 
-  if (data->m_config->m_prefetchcount > 0 && header.hasKey(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER))) {
+  if (data->m_config->m_prefetchcount > 0 && header.hasKey(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size())) {
     data->m_prefetchable = true;
   }
 
diff --git a/plugins/experimental/slice/util.cc b/plugins/experimental/slice/util.cc
index 97183716863..080d011488d 100644
--- a/plugins/experimental/slice/util.cc
+++ b/plugins/experimental/slice/util.cc
@@ -87,10 +87,10 @@ request_block(TSCont contp, Data *const data)
     return false;
   }
 
-  header.removeKey(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER));
+  header.removeKey(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size());
   if (data->m_blocknum == 0 && data->m_config->m_prefetchcount > 0) {
-    std::string valStr = "-";
-    header.setKeyVal(SLICE_CRR_HEADER, strlen(SLICE_CRR_HEADER), valStr.c_str(), valStr.length());
+    std::string valStr = "1";
+    header.setKeyVal(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), valStr.c_str(), valStr.length());
   }
 
   // create virtual connection back into ATS

From f12e0e6b7e1a232edadce1ae33d185c5a5c23937 Mon Sep 17 00:00:00 2001
From: Serris Lew <lserris@apple.com>
Date: Wed, 27 Jul 2022 09:45:10 -0700
Subject: [PATCH 9/9] update header val type

---
 plugins/cache_range_requests/cache_range_requests.cc | 5 +++--
 plugins/experimental/slice/HttpHeader.h              | 1 +
 plugins/experimental/slice/util.cc                   | 3 +--
 3 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/plugins/cache_range_requests/cache_range_requests.cc b/plugins/cache_range_requests/cache_range_requests.cc
index 36b81c6f4ec..46539f370ad 100644
--- a/plugins/cache_range_requests/cache_range_requests.cc
+++ b/plugins/cache_range_requests/cache_range_requests.cc
@@ -49,6 +49,7 @@ using parent_select_mode_t = enum parent_select_mode {
 
 constexpr std::string_view DefaultImsHeader = {"X-Crr-Ims"};
 constexpr std::string_view SLICE_CRR_HEADER = {"Slice-Crr-Status"};
+constexpr std::string_view SLICE_CRR_VAL    = "1";
 
 struct pluginconfig {
   parent_select_mode_t ps_mode{PS_DEFAULT};
@@ -383,8 +384,8 @@ handle_client_send_response(TSHttpTxn txnp, txndata *const txn_state)
 
       remove_header(resp_buf, resp_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size());
       if (txn_state->slice_response) {
-        std::string valStr = "1";
-        set_header(resp_buf, resp_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), valStr.c_str(), valStr.length());
+        set_header(resp_buf, resp_loc, SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), SLICE_CRR_VAL.data(),
+                   SLICE_CRR_VAL.size());
       }
     } else {
       DEBUG_LOG("Ignoring status code %d; txn_state->origin_status=%d", status, txn_state->origin_status);
diff --git a/plugins/experimental/slice/HttpHeader.h b/plugins/experimental/slice/HttpHeader.h
index 9c4be14d760..81f1817fb73 100644
--- a/plugins/experimental/slice/HttpHeader.h
+++ b/plugins/experimental/slice/HttpHeader.h
@@ -37,6 +37,7 @@
 #include <string>
 
 constexpr std::string_view SLICE_CRR_HEADER = {"Slice-Crr-Status"};
+constexpr std::string_view SLICE_CRR_VAL    = "1";
 
 /**
   Designed to be a cheap throwaway struct which allows a
diff --git a/plugins/experimental/slice/util.cc b/plugins/experimental/slice/util.cc
index 080d011488d..f9c74ed1aea 100644
--- a/plugins/experimental/slice/util.cc
+++ b/plugins/experimental/slice/util.cc
@@ -89,8 +89,7 @@ request_block(TSCont contp, Data *const data)
 
   header.removeKey(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size());
   if (data->m_blocknum == 0 && data->m_config->m_prefetchcount > 0) {
-    std::string valStr = "1";
-    header.setKeyVal(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), valStr.c_str(), valStr.length());
+    header.setKeyVal(SLICE_CRR_HEADER.data(), SLICE_CRR_HEADER.size(), SLICE_CRR_VAL.data(), SLICE_CRR_VAL.size());
   }
 
   // create virtual connection back into ATS