Method to get exit time of process

NEWS.md

@@ -1,5 +1,8 @@
 # processx (development version)
 
+* New `process$get_end_time()` method returns the time when the process
+  exited as a `POSIXct`, or `NULL` if it is still running (#218).
+
 * `process$new()` and `run()` now support `pty = TRUE` on Windows 10 version
   1809 and later, in addition to Unix. The Windows implementation uses the
   ConPTY API (`CreatePseudoConsole`). The API is loaded dynamically so

R/process.R

@@ -381,6 +381,17 @@ process <- R6::R6Class(
 
     get_start_time = function() process_get_start_time(self, private),
 
+    #' @description
+    #' `$get_end_time()` returns the time when the process finished,
+    #' or `NULL` if it is still running.
+    #' On Unix the timestamp is recorded when R first notices the exit
+    #' (via the `SIGCHLD` handler or a call to `$is_alive()`,
+    #' `$get_exit_status()`, or `$wait()`), so it may be slightly later
+    #' than the actual kernel exit time.
+    #' On Windows the exact kernel exit time is used.
+
+    get_end_time = function() process_get_end_time(self, private),
+
     #' @description
     #' `$is_supervised()` returns whether the process is being tracked by
     #' supervisor process.
@@ -726,6 +737,7 @@ process <- R6::R6Class(
     cleanfiles = NULL, # which temp stdout/stderr file(s) to clean up
     wd = NULL, # working directory (or NULL for current)
     starttime = NULL, # timestamp of start
+    endtime = NULL, # timestamp of exit, or 0 if not yet exited
     echo_cmd = NULL, # whether to echo the command
     windows_verbatim_args = NULL,
     windows_hide_window = NULL,
@@ -848,6 +860,18 @@ process_get_start_time <- function(self, private) {
   format_unix_time(private$starttime)
 }
 
+process_get_end_time <- function(self, private) {
+  if (!is.null(private$endtime)) {
+    return(private$endtime)
+  }
+  et <- chain_call(c_processx__proc_end_time, private$status)
+  if (is.null(et)) {
+    return(NULL)
+  }
+  private$endtime <- format_unix_time(et)
+  private$endtime
+}
+
 process_get_pid <- function(self, private) {
   chain_call(c_processx_get_pid, private$status)
 }

src/create-time.c

@@ -261,3 +261,17 @@ SEXP processx__proc_start_time(SEXP status) {
 
   return ScalarReal(handle->create_time);
 }
+
+SEXP processx__proc_end_time(SEXP status) {
+  processx_handle_t *handle = R_ExternalPtrAddr(status);
+
+  if (!handle) {
+    R_THROW_ERROR("Internal processx error, handle already removed");
+  }
+
+  if (handle->end_time == 0.0) {
+    return R_NilValue;
+  } else {
+    return ScalarReal(handle->end_time);
+  }
+}

src/init.c

@@ -80,6 +80,7 @@ static const R_CallMethodDef callMethods[]  = {
   { "processx_create_named_pipe",  (DL_FUNC) &processx_create_named_pipe,  2 },
   { "processx_write_named_pipe",   (DL_FUNC) &processx_write_named_pipe,   2 },
   { "processx__proc_start_time",   (DL_FUNC) &processx__proc_start_time,   1 },
+  { "processx__proc_end_time",     (DL_FUNC) &processx__proc_end_time,     1 },
   { "processx__set_boot_time",     (DL_FUNC) &processx__set_boot_time,     1 },
 
   { "processx_connection_create",     (DL_FUNC) &processx_connection_create,     2 },

src/processx.h

@@ -61,6 +61,7 @@ SEXP processx_poll(SEXP statuses, SEXP conn, SEXP ms);
 
 SEXP processx__process_exists(SEXP pid);
 SEXP processx__proc_start_time(SEXP status);
+SEXP processx__proc_end_time(SEXP status);
 SEXP processx__unload_cleanup(void);
 
 SEXP processx_is_named_pipe_open(SEXP pipe_ext);

src/unix/processx-unix.h

@@ -24,6 +24,7 @@ typedef struct processx_handle_s {
   int waitpipe[2];		/* use it for wait() with timeout */
   int cleanup;
   double create_time;
+  double end_time;          /* 0.0 until the process exits */
   processx_connection_t *pipes[3];
   int ptyfd;
   int pty_child_fd; /* parent holds child PTY fd open to prevent data loss on macOS */

src/unix/processx.c

@@ -8,6 +8,7 @@
 #include <stdlib.h>
 #include <fcntl.h>
 #include <stdio.h>
+#include <time.h>
 
 #include "../processx.h"
 #include "../cleancall.h"
@@ -652,6 +653,15 @@ void processx__collect_exit_status(SEXP status, int retval, int wstat) {
     handle->exitcode = - WTERMSIG(wstat);
   }
 
+  {
+    struct timespec _et;
+    if (clock_gettime(CLOCK_REALTIME, &_et) == 0) {
+      handle->end_time = (double)_et.tv_sec + (double)_et.tv_nsec * 1e-9;
+    } else {
+      handle->end_time = NA_REAL;
+    }
+  }
+
   handle->collected = 1;
 
   /* Now that the child has exited, release our hold on the PTY child fd.

src/win/processx-win.h

@@ -14,6 +14,7 @@ typedef struct processx_handle_s {
   processx_connection_t *pipes[3];
   int cleanup;
   double create_time;
+  double end_time;          /* 0.0 until the process exits */
   void *ptycon;           /* ConPTY handle (HPCON), NULL if not using PTY */
 } processx_handle_t;
 

src/win/processx.c

@@ -1418,6 +1418,18 @@ void processx__collect_exit_status(SEXP status, DWORD exitcode) {
   processx_handle_t *handle = R_ExternalPtrAddr(status);
   handle->exitcode = exitcode;
   handle->collected = 1;
+  {
+    FILETIME ftCreate, ftExit, ftKernel, ftUser;
+    if (GetProcessTimes(handle->hProcess,
+                        &ftCreate, &ftExit, &ftKernel, &ftUser)) {
+      long long ll = ((LONGLONG)ftExit.dwHighDateTime) << 32;
+      ll += ftExit.dwLowDateTime - 116444736000000000LL;
+      handle->end_time = (double)(ll / 10000000) +
+                         (double)(ll % 10000000) / 10000000.0;
+    } else {
+      handle->end_time = 0.0;
+    }
+  }
   /* Do NOT call ClosePseudoConsole() here.  ConPTY processes the child's
      writes asynchronously: by the time GetExitCodeProcess() reports that
      the child has exited, conhost may not have finished writing the child's

tests/testthat/_snaps/Darwin/process.md

@@ -6,7 +6,7 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<tempdir>/<tempfile>' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<tempdir>/<tempfile>' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 
 # working directory does not exist
 
@@ -16,5 +16,5 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 

tests/testthat/_snaps/Darwin/run.md

@@ -6,5 +6,5 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 

tests/testthat/_snaps/Linux/process.md

@@ -6,7 +6,7 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<tempdir>/<tempfile>' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<tempdir>/<tempfile>' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 
 # working directory does not exist
 
@@ -16,5 +16,5 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 

tests/testthat/_snaps/Linux/run.md

@@ -6,5 +6,5 @@
       Error:
       ! ! Native call to `processx_exec` failed
       Caused by error in `chain_call(c_processx_exec, command, c(command, args), pty, pty_options, ...` at initialize.R:<line>:<col>:
-      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:628 (processx_exec)
+      ! cannot start processx process '<path>/px' (system error 2, No such file or directory) @unix/processx.c:629 (processx_exec)
 

tests/testthat/test-process.R

@@ -131,3 +131,24 @@ test_that("R process is installed with a SIGTERM cleanup handler", {
   # Was not cleaned up
   expect_true(dir.exists(p_temp_dir))
 })
+
+test_that("get_end_time", {
+  px <- get_tool("px")
+
+  p <- process$new(px, c("sleep", "1"))
+  on.exit(p$kill(), add = TRUE)
+
+  before <- Sys.time()
+  expect_null(p$get_end_time())
+
+  p$wait()
+  after <- Sys.time()
+
+  et <- p$get_end_time()
+  expect_s3_class(et, "POSIXct")
+  expect_gte(as.double(et), as.double(before))
+  expect_gte(as.double(et), as.double(p$get_start_time()))
+
+  # cached: second call returns the same value
+  expect_equal(p$get_end_time(), et)
+})