Add sharding to DM.

dm/DM.cpp

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "CrashHandler.h"
 #include "DMJsonWriter.h"
 #include "DMSrcSink.h"
@@ skipping 28 matching lines @@
         "Space-separated config/src/srcOptions/name quadruples to blacklist.  '_' matches anything.  E.g. \n"
         "'--blacklist gpu skp _ _' will blacklist all SKPs drawn into the gpu config.\n"
         "'--blacklist gpu skp _ _ 8888 gm _ aarects' will also blacklist the aarects GM on 8888.");
 
 DEFINE_string2(readPath, r, "", "If set check for equality with golden results in this directory.");
 
 DEFINE_string(uninterestingHashesFile, "",
         "File containing a list of uninteresting hashes. If a result hashes to something in "
         "this list, no image is written for that result.");
 
+DEFINE_int32(shards, 1, "We're splitting source data into this many shards.");
+DEFINE_int32(shard,  0, "Which shard do I run?");
+
 __SK_FORCE_IMAGE_DECODER_LINKING;
 using namespace DM;
 
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 SK_DECLARE_STATIC_MUTEX(gFailuresMutex);
 static SkTArray<SkString> gFailures;
 
 static void fail(ImplicitString err) {
     SkAutoMutexAcquire lock(gFailuresMutex);
@@ skipping 101 matching lines @@
 struct Tagged : public SkAutoTDelete<T> {
   const char* tag;
   const char* options;
 };
 
 static const bool kMemcpyOK = true;
 
 static SkTArray<Tagged<Src>,  kMemcpyOK>  gSrcs;
 static SkTArray<Tagged<Sink>, kMemcpyOK> gSinks;
 
+static bool in_shard() {
+    static int N = 0;
+    return N++ % FLAGS_shards == FLAGS_shard;
+}
+
 static void push_src(const char* tag, const char* options, Src* s) {
     SkAutoTDelete<Src> src(s);
-    if (FLAGS_src.contains(tag) &&
+    if (in_shard() &&
+        FLAGS_src.contains(tag) &&
         !SkCommandLineFlags::ShouldSkip(FLAGS_match, src->name().c_str())) {
         Tagged<Src>& s = gSrcs.push_back();
         s.reset(src.detach());
         s.tag = tag;
         s.options = options;
     }
 }
 
 static void push_codec_srcs(Path path) {
     SkAutoTUnref<SkData> encoded(SkData::NewFromFileName(path.c_str()));
@@ skipping 413 matching lines @@
 /*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/
 
 // Unit tests don't fit so well into the Src/Sink model, so we give them special treatment.
 
 static SkTDArray<skiatest::Test> gThreadedTests, gGPUTests;
 
 static void gather_tests() {
     if (!FLAGS_src.contains("tests")) {
         return;
     }
-    for (const skiatest::TestRegistry* r = skiatest::TestRegistry::Head(); r;
-         r = r->next()) {
+    for (const skiatest::TestRegistry* r = skiatest::TestRegistry::Head(); r; r = r->next()) {
+        if (!in_shard()) {
+            continue;
+        }
         // Despite its name, factory() is returning a reference to
         // link-time static const POD data.
         const skiatest::Test& test = r->factory();
         if (SkCommandLineFlags::ShouldSkip(FLAGS_match, test.name)) {
             continue;
         }
         if (test.needsGpu && gpu_supported()) {
             (FLAGS_gpu_threading ? gThreadedTests : gGPUTests).push(test);
         } else if (!test.needsGpu && FLAGS_cpu) {
             gThreadedTests.push(test);
@@ skipping 126 matching lines @@
     }
     return 0;
 }
 
 #if !defined(SK_BUILD_FOR_IOS)
 int main(int argc, char** argv) {
     SkCommandLineFlags::Parse(argc, argv);
     return dm_main();
 }
 #endif