Add zPages Tracez Processor

CMakeLists.txt

@@ -56,3 +56,4 @@ add_subdirectory(sdk)
 include_directories(.)
 add_subdirectory(exporters)
 add_subdirectory(examples)
+add_subdirectory(ext)

ext/BUILD

@@ -0,0 +1,7 @@
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "headers",
+    hdrs = glob(["include/**/*.h"]),
+    strip_include_prefix = "include",
+)

ext/CMakeLists.txt

@@ -0,0 +1,5 @@
+add_subdirectory(src)
+
+if(BUILD_TESTING)
+  add_subdirectory(test)
+endif()

ext/include/opentelemetry/ext/zpages/tracez_processor.h

@@ -0,0 +1,93 @@
+#pragma once
+
+#include <chrono>
+#include <memory>
+#include <mutex>
+#include <unordered_set>
+#include <vector>
+#include <utility>
+
+#include "opentelemetry/sdk/trace/processor.h"
+#include "opentelemetry/sdk/trace/recordable.h"
+#include "opentelemetry/sdk/trace/span_data.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace ext
+{
+namespace zpages
+{
+/*
+ * The span processor passes and stores running and completed recordables (casted as span_data)
+ * to be used by the TraceZ Data Aggregator.
+ */
+class TracezSpanProcessor : public opentelemetry::sdk::trace::SpanProcessor {
+ public:
+
+  struct CollectedSpans {
+    std::unordered_set<opentelemetry::sdk::trace::SpanData*> running;
+    std::vector<std::unique_ptr<opentelemetry::sdk::trace::SpanData>> completed;
+  };
+
+  /*
+   * Initialize a span processor.
+   */
+  explicit TracezSpanProcessor() noexcept {}
+
+  /*
+   * Create a span recordable, which is span_data
+   * @return a newly initialized recordable
+   */
+  std::unique_ptr<opentelemetry::sdk::trace::Recordable> MakeRecordable() noexcept override
+  {
+    return std::unique_ptr<opentelemetry::sdk::trace::Recordable>(new opentelemetry::sdk::trace::SpanData);
+  }
+
+  /*
+   * OnStart is called when a span starts; the recordable is cast to span_data and added to running_spans.
+   * @param span a recordable for a span that was just started
+   */
+  void OnStart(opentelemetry::sdk::trace::Recordable &span) noexcept override;
+
+  /*
+   * OnEnd is called when a span ends; that span_data is moved from running_spans to
+   * completed_spans
+   * @param span a recordable for a span that was ended
+   */
+  void OnEnd(std::unique_ptr<opentelemetry::sdk::trace::Recordable> &&span) noexcept override;
+
+  /*
+   * Returns a snapshot of all spans stored. This snapshot has a copy of the
+   * stored running_spans and gives ownership of completed spans to the caller.
+   * Stored completed_spans are cleared from the processor. Currently,
+   * copy-on-write is utilized where possible to minimize contention, but locks
+   * may be added in the future.
+   * @return snapshot of all currently running spans and newly completed spans
+   * (spans never sent while complete) at the time that the function is called
+   */
+  CollectedSpans GetSpanSnapshot() noexcept;
+
+  /*
+   * For now, does nothing. In the future, it
+   * may send all ended spans that have not yet been sent to the aggregator.
+   * @param timeout an optional timeout, the default timeout of 0 means that no
+   * timeout is applied. Currently, timeout does nothing.
+   */
+  void ForceFlush(
+      std::chrono::microseconds timeout = std::chrono::microseconds(0)) noexcept override {}
+
+  /*
+   * Shut down the processor and do any cleanup required, which is none.
+   * After the call to Shutdown, subsequent calls to OnStart, OnEnd, ForceFlush
+   * or Shutdown will return immediately without doing anything.
+   * @param timeout an optional timeout, the default timeout of 0 means that no
+   * timeout is applied. Currently, timeout does nothing.
+   */
+  void Shutdown(std::chrono::microseconds timeout = std::chrono::microseconds(0)) noexcept override {}
+
+ private:
+  mutable std::mutex mtx_;
+  CollectedSpans spans_;
+};
+}  // namespace zpages
+}  // namespace ext
+OPENTELEMETRY_END_NAMESPACE

ext/src/CMakeLists.txt

@@ -0,0 +1 @@
+add_subdirectory(zpages)

ext/src/zpages/BUILD

@@ -0,0 +1,27 @@
+# Copyright 2020, OpenTelemetry Authors
+#
+# Licensed 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.
+
+package(default_visibility = ["//visibility:public"])
+
+cc_library(
+    name = "zpages",
+    srcs = glob(["**/*.cc"]),
+    hdrs = glob(["**/*.h"]),
+    include_prefix = "ext/zpages",
+    deps = [
+        "//api",
+        "//sdk:headers",
+        "//ext:headers",
+    ],
+)

ext/src/zpages/CMakeLists.txt

@@ -0,0 +1,8 @@
+add_library(opentelemetry_zpages
+	tracez_processor.cc
+	../../include/opentelemetry/ext/zpages/tracez_processor.h)
+
+target_include_directories(opentelemetry_zpages PUBLIC ../../include)
+
+target_link_libraries(opentelemetry_zpages opentelemetry_api opentelemetry_trace)
+

ext/src/zpages/README.md

@@ -1,34 +1,33 @@
 # zPages
-> Last updated 6/26/20
 
-# Table of Contents
+## Table of Contents
 - [Summary](#summary)
   - [TraceZ](#tracez)
   - [RPCz](#rpcz)
 - [Usage](#usage)
 - [Links of Interest](#links-of-interest)
 
 ## Summary
-zPages allow easy viewing of tracing information. When included for a process, zPages will display basic information about that process on a webpage. There are currently two types of zPages: TraceZ and RPCz.
+zPages allow easy viewing of tracing information. When included for a process, zPages will display basic information about that process on a webpage. Two types of zPages include TraceZ and RPCz.
 
-Including a zPage within a page is useful for developers because it's quicker to get running than adding extra code and installing external exporters like Jaeger and Zipkin. zPages tend to be more lightweight than these external exporters, but are also helpful for debugging latency issues and deadlocks.
+Including a zPage within a page is useful for developers because it's quicker to get running than adding extra code and installing external exporters like Jaeger and Zipkin. zPages tend to be more lightweight than these external exporters, but are also helpful for debugging latency issues (slow parts of applications) and deadlocks (running spans that don't end).
 
 The idea of "zPages" originates from one of OpenTelemetry's predecessors, [OpenCensus](https://opencensus.io/). You can read more about it [here](https://opencensus.io/zpages). OpenCensus has different zPage implementations in [Java](https://opencensus.io/zpages/java/), [Go](https://opencensus.io/zpages/go/), and [Node](https://opencensus.io/zpages/node/) and there has been similar internal solutions developed at companies like Uber, but *this is the first major open-source implementation of zPages in C++*. Within OpenTelemetry, zPages are also being developed in [Java](https://github.com/open-telemetry/opentelemetry-java).
 
 #### How It Works
-On a high level, zPages work by reading a process' spans using a SpanProcessor, which exports spans to the appropriate DataAggregator that a HttpServer uses.
+On a high level, an application creates spans using a Tracer Provider/Tracer who passes them to a Span Processor, which exports spans to the appropriate Data Aggregator that a Http Server displays information for.
 
 > TODO: Add picture examples for span overview and individual span view
 
 ### TraceZ
 TraceZ is a type of zPage that shows information on tracing spans, and allows users to look closer at specific and individual spans. Details a user would view include span id, name, status, and timestamps. The individual components of TraceZ are as follows:
 
 - TracezSpanProcessor (TSP)
-  - Contact point for TraceZ to connect with a process, which collects tracing information and provides an interface for TDA.
+  - A tracer/tracer provider (which the user chooses) creates spans, which connects to TSP so that TraceZ to detect spans. The TSP then stores tracing information in running and completed containers and provides an interface for TDA to access their information.
 - TracezDataAggregator (TDA)
-  - Intermediary between the TSP and THS, which also performs various functions and calculations to send the correct tracing information to the THS.
+  - Intermediary between the TSP and THS, which also performs various functions and calculations (mainly grouping spans by their names and latency times) to send the correct tracing information to the THS.
 - TracezHttpServer (THS)
-  - User-facing web page generator, which creates HTML pages using TDA that display 1) overall information on all of the process's spans and 2) more detailed information on specific spans when clicked.
+  - User-facing web page generator, which creates HTML pages using TDA that display 1) overall information and trends on all of the process's spans and 2) more detailed information on specific spans when clicked.
 
 ### RPCz
 RPCz is a type of zPage that provides details on instrumented sent and received RPC messages. Although there is currently no ongoing development of RPCz for OpenTelemetry, OpenCensus zPages have implementations of RPCz (linked above).
@@ -41,6 +40,6 @@ RPCz is a type of zPage that provides details on instrumented sent and received
 - [TracezSpanProcessor Design Doc](https://docs.google.com/document/d/1kO4iZARYyr-EGBlY2VNM3ELU3iw6ZrC58Omup_YT-fU/edit#) (pending review)
 - [TracezDataAggregator Design Doc](https://docs.google.com/document/d/1ziKFgvhXFfRXZjOlAHQRR-TzcNcTXzg1p2I9oPCEIoU/edit?ts=5ef0d177#heading=h.5irk4csrpu0y) (pending review)
 - [TracezHttpServer Design Doc](https://docs.google.com/document/d/1U1V8QZ5LtGl4Mich-aJ6KZGLHrMIE8pWyspmzvnIefI/edit#) (draft)
-- [Contribution Guidelines](https://github.com/open-telemetry/opentelemetry-cpp/blob/master/CONTRIBUTING.md)
-
-
+- [zPages General Direction Spec](https://github.com/open-telemetry/oteps/blob/master/text/0110-z-pages.md)
+- [Prospective Fields Displayed by
+  TraceZ](https://github.com/open-telemetry/opentelemetry-cpp/blob/master/sdk/include/opentelemetry/sdk/trace/span_data.h)

ext/src/zpages/tracez_processor.cc

@@ -0,0 +1,38 @@
+#include "opentelemetry/ext/zpages/tracez_processor.h"
+
+OPENTELEMETRY_BEGIN_NAMESPACE
+namespace ext {
+namespace zpages {
+
+  void TracezSpanProcessor::OnStart(opentelemetry::sdk::trace::Recordable &span) noexcept {
+    std::lock_guard<std::mutex> lock(mtx_);
+    spans_.running.insert(static_cast<opentelemetry::sdk::trace::SpanData*>(&span));
+  }
+
+  void TracezSpanProcessor::OnEnd(std::unique_ptr<opentelemetry::sdk::trace::Recordable> &&span) noexcept {
+    if (span == nullptr) return;
+    auto span_raw = static_cast<opentelemetry::sdk::trace::SpanData*>(span.get());
+    std::lock_guard<std::mutex> lock(mtx_);
+    auto span_it = spans_.running.find(span_raw);
+    if (span_it != spans_.running.end()) {
+      spans_.running.erase(span_it);
+      spans_.completed.push_back(
+          std::unique_ptr<opentelemetry::sdk::trace::SpanData>(
+              static_cast<opentelemetry::sdk::trace::SpanData*>(span.release())));
+    }
+  }
+
+
+  TracezSpanProcessor::CollectedSpans TracezSpanProcessor::GetSpanSnapshot() noexcept {
+    CollectedSpans snapshot;
+    std::lock_guard<std::mutex> lock(mtx_);
+    snapshot.running = spans_.running;
+    snapshot.completed = std::move(spans_.completed);
+    spans_.completed.clear();
+    return snapshot;
+  }
+
+
+}  // namespace zpages
+}  // namespace ext
+OPENTELEMETRY_END_NAMESPACE

ext/test/CMakeLists.txt

@@ -0,0 +1 @@
+add_subdirectory(zpages)

ext/test/zpages/BUILD

@@ -0,0 +1,11 @@
+cc_test(
+    name = "tracez_processor_tests",
+    srcs = [
+        "tracez_processor_test.cc",
+    ],
+    deps = [
+        "//sdk/src/trace",
+        "//ext/src/zpages",
+        "@com_google_googletest//:gtest_main",
+    ],
+)

ext/test/zpages/CMakeLists.txt

@@ -0,0 +1,13 @@
+foreach(testname
+	tracez_processor_test)
+  add_executable(${testname} "${testname}.cc")
+  target_link_libraries(
+    ${testname} ${GTEST_BOTH_LIBRARIES} ${CMAKE_THREAD_LIBS_INIT}
+    opentelemetry_zpages)
+
+  gtest_add_tests(
+    TARGET ${testname}
+    TEST_PREFIX ext.
+    TEST_LIST ${testname})
+endforeach()
+