Apply multiprocessing to capture_replay_tests.py

doc/CaptureAndReplay.md

@@ -165,4 +165,15 @@ as the GLES driver for your application.
     ```
     $ autoninja -C out/Release capture_replay_sample
     $ out/Release/capture_replay_sample
-    ```
+    ```
\ No newline at end of file
+
+## Testing
+
+### Regression Testing Architecture
+The python script uses the job queue pattern. There are n processes running asynchronously and independently, one on each CPU core. Whenever a process (except for the main process) finishes a job and becomes available, it grabs the next job from a shared job queue and runs that job on its CPU core. They keep doing this until there is no more job in the shared job queue. The main process, after filling up the shared job queue and spawning the (n-1) subprocesses that run on the remaining (n-1) CPU cores, waits until all the subprocesses are finished. It then reports the results and cleans up.
+
+![Point-in-time snapshot of the job queue](https://screenshot.googleplex.com/w2QY5ui5FMg.png)
+
+### Job unit
+A job unit is a test batch. Each test has to go through 3 stages: capture run, replay build, and replay run. The test batch batches the replay build stage of multiple tests together, and the replay run stage of multiple tests together.
+![A test batch as a job unit](https://screenshot.googleplex.com/A4w8ogsnfLw.png)

src/tests/capture_replay_tests/BUILD.gn

@@ -9,6 +9,9 @@ declare_args() {
 
   # Decide which context to replay, starting with desktop default
   angle_capture_replay_test_context_id = 1
+
+  #Set the trace directory. Default is traces
+  angle_capture_replay_test_trace_dir = "traces"
 }
 
 if (angle_build_capture_replay_tests) {
@@ -17,15 +20,17 @@ if (angle_build_capture_replay_tests) {
   angle_executable("capture_replay_tests") {
     testonly = true
     _contextid = angle_capture_replay_test_context_id
+    _trace_folder_relative_path = "./" + angle_capture_replay_test_trace_dir
     _trace_sources =
-        read_file("traces/angle_capture_context${_contextid}_files.txt",
+        read_file(_trace_folder_relative_path +
+                      "/angle_capture_context${_contextid}_files.txt",
                   "list lines") +
         [
           "angle_capture_context${_contextid}.cpp",
           "angle_capture_context${_contextid}.h",
         ]
-    sources =
-        rebase_path(_trace_sources, ".", "traces") + [ "CaptureReplayTest.cpp" ]
+    sources = rebase_path(_trace_sources, ".", _trace_folder_relative_path) +
+              [ "CaptureReplayTest.cpp" ]
     deps = [
       "$angle_root:angle_common",
       "$angle_root:angle_compression",
@@ -44,11 +49,11 @@ if (angle_build_capture_replay_tests) {
       suppressed_configs += [ "//build/config/compiler:default_optimization" ]
       configs += [ "//build/config/compiler:no_optimize" ]
     }
-    _data_path = rebase_path("traces", root_out_dir)
+    _data_path = rebase_path(_trace_folder_relative_path, root_out_dir)
     defines = [
       "ANGLE_CAPTURE_REPLAY_TEST_DATA_DIR=\"${_data_path}\"",
       "ANGLE_CAPTURE_REPLAY_TEST_CONTEXT_ID=${_contextid}",
-      "ANGLE_CAPTURE_REPLAY_TEST_HEADER=traces/angle_capture_context${_contextid}.h",
+      "ANGLE_CAPTURE_REPLAY_TEST_HEADER=" + "${angle_capture_replay_test_trace_dir}/angle_capture_context${_contextid}.h",
     ]
   }
 } else {