SkThreadPool ~~> SkTaskGroup

SkTaskGroup is like SkThreadPool except the threads stay in
one global pool.  Each SkTaskGroup itself is tiny (4 bytes)
and its wait() method applies only to tasks add()ed to that
instance, not the whole thread pool.

This means we don't need to bring up new thread pools when
tests themselves want to use multithreading (e.g. pathops,
quilt).  We just create a new SkTaskGroup and wait for that
to complete.  This should be more efficient, and allow us
to expand where we use threads to really latency sensitive
places.  E.g. we can probably now use these in nanobench
for CPU .skp rendering.

Now that all threads are sharing the same pool, I think we
can remove most of the custom mechanism pathops tests use
to control threading.  They'll just ride on the global pool
with all other tests now.

This (temporarily?) removes the GPU multithreading feature
from DM, which we don't use.

On my desktop, DM runs a little faster (57s -> 55s) in
Debug, and a lot faster in Release (36s -> 24s).  The bots
show speedups of similar proportions, cutting more than a
minute off the N4/Release and Win7/Debug runtimes.

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/9c7207b5dc71dc5a96a2eb107d401133333d5b6f

R=caryclark@google.com, bsalomon@google.com, bungeman@google.com, mtklein@google.com, reed@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/531653002

5 files changed, 10 insertions, 18 deletions

diff --git a/tools/flags/SkCommonFlags.cpp b/tools/flags/SkCommonFlags.cpp
index 4d08ba6340..7776c36a59 100644
--- a/tools/flags/SkCommonFlags.cpp
+++ b/tools/flags/SkCommonFlags.cpp
@@ -6,7 +6,6 @@
  */
 
 #include "SkCommonFlags.h"
-#include "SkThreadPool.h"
 
 DEFINE_string(config, "565 8888 pdf gpu nonrendering angle",
               "Options: 565 8888 pdf gpu nonrendering msaa4 msaa16 nvprmsaa4 nvprmsaa16 "
@@ -42,12 +41,10 @@ DEFINE_bool(resetGpuContext, true, "Reset the GrContext before running each test
 DEFINE_bool(abandonGpuContext, false, "Abandon the GrContext after running each test. "
                                       "Implies --resetGpuContext.");
 
-DEFINE_bool2(single, z, false, "run tests on a single thread internally.");
-
 DEFINE_string(skps, "skps", "Directory to read skps from.");
 
-DEFINE_int32(threads, SkThreadPool::kThreadPerCore,
-             "run threadsafe tests on a threadpool with this many threads.");
+DEFINE_int32(threads, 0, "Run threadsafe tests on a threadpool with this many threads, "
+                         "defaulting to one thread per core.");
 
 DEFINE_bool2(verbose, v, false, "enable verbose output from the test driver.");
 
diff --git a/tools/flags/SkCommonFlags.h b/tools/flags/SkCommonFlags.h
index b45ef0738a..ecd4148448 100644
--- a/tools/flags/SkCommonFlags.h
+++ b/tools/flags/SkCommonFlags.h
@@ -20,7 +20,6 @@ DECLARE_string(match);
 DECLARE_bool(quiet);
 DECLARE_bool(resetGpuContext);
 DECLARE_bool(abandonGpuContext);
-DECLARE_bool(single);
 DECLARE_string(skps);
 DECLARE_int32(threads);
 DECLARE_string(resourcePath);
diff --git a/tools/iOSShell.cpp b/tools/iOSShell.cpp
index 49be34d65b..8656e645aa 100644
--- a/tools/iOSShell.cpp
+++ b/tools/iOSShell.cpp
@@ -12,7 +12,6 @@
 #include "SkCanvas.h"
 #include "SkCommonFlags.h"
 #include "SkGraphics.h"
-#include "SkThreadPool.h"
 #include "SkWindow.h"
 #include "sk_tool_utils.h"
 
diff --git a/tools/skpdiff/SkDiffContext.cpp b/tools/skpdiff/SkDiffContext.cpp
index 42d20de19d..78d8400968 100644
--- a/tools/skpdiff/SkDiffContext.cpp
+++ b/tools/skpdiff/SkDiffContext.cpp
@@ -12,7 +12,7 @@
 #include "SkSize.h"
 #include "SkStream.h"
 #include "SkTDict.h"
-#include "SkThreadPool.h"
+#include "SkTaskGroup.h"
 
 // from the tools directory for replace_char(...)
 #include "picture_utils.h"
@@ -24,7 +24,6 @@
 SkDiffContext::SkDiffContext() {
     fDiffers = NULL;
     fDifferCount = 0;
-    fThreadCount = SkThreadPool::kThreadPerCore;
 }
 
 SkDiffContext::~SkDiffContext() {
@@ -87,7 +86,7 @@ static SkString get_common_prefix(const SkString& a, const SkString& b) {
 }
 
 static SkString get_combined_name(const SkString& a, const SkString& b) {
-    // Note (stephana): We must keep this function in sync with 
+    // Note (stephana): We must keep this function in sync with
     // getImageDiffRelativeUrl() in static/loader.js (under rebaseline_server).
     SkString result = a;
     result.append("-vs-");
@@ -238,7 +237,7 @@ void SkDiffContext::diffDirectories(const char baselinePath[], const char testPa
         return;
     }
 
-    SkThreadPool threadPool(fThreadCount);
+    SkTaskGroup tg;
     SkTArray<SkThreadedDiff> runnableDiffs;
     runnableDiffs.reset(baselineEntries.count());
 
@@ -253,13 +252,11 @@ void SkDiffContext::diffDirectories(const char baselinePath[], const char testPa
         if (sk_exists(testFile.c_str()) && !sk_isdir(testFile.c_str())) {
             // Queue up the comparison with the differ
             runnableDiffs[x].setup(this, baselineFile, testFile);
-            threadPool.add(&runnableDiffs[x]);
+            tg.add(&runnableDiffs[x]);
         } else {
             SkDebugf("Baseline file \"%s\" has no corresponding test file\n", baselineFile.c_str());
         }
     }
-
-    threadPool.wait();
 }
 
 
@@ -284,16 +281,14 @@ void SkDiffContext::diffPatterns(const char baselinePattern[], const char testPa
         return;
     }
 
-    SkThreadPool threadPool(fThreadCount);
+    SkTaskGroup tg;
     SkTArray<SkThreadedDiff> runnableDiffs;
     runnableDiffs.reset(baselineEntries.count());
 
     for (int x = 0; x < baselineEntries.count(); x++) {
         runnableDiffs[x].setup(this, baselineEntries[x], testEntries[x]);
-        threadPool.add(&runnableDiffs[x]);
+        tg.add(&runnableDiffs[x]);
     }
-
-    threadPool.wait();
 }
 
 void SkDiffContext::outputRecords(SkWStream& stream, bool useJSONP) {
diff --git a/tools/skpdiff/skpdiff_main.cpp b/tools/skpdiff/skpdiff_main.cpp
index 6c40552d33..9c1f37f243 100644
--- a/tools/skpdiff/skpdiff_main.cpp
+++ b/tools/skpdiff/skpdiff_main.cpp
@@ -27,6 +27,7 @@
 #include "SkGraphics.h"
 #include "SkStream.h"
 #include "SkTDArray.h"
+#include "SkTaskGroup.h"
 
 #include "SkDifferentPixelsMetric.h"
 #include "SkDiffContext.h"
@@ -125,6 +126,7 @@ int tool_main(int argc, char * argv[]) {
 
     // Needed by various Skia components
     SkAutoGraphics ag;
+    SkTaskGroup::Enabler enabled;
 
     if (FLAGS_list) {
         SkDebugf("Available Metrics:\n");