Create module system for VisualBench

The newly created VisualLightweightBenchModule is just the old VisualBench.cpp, but gutted to only include timing code.

Future CLs will harden this abstraction, but for this CL the module owns a backpointer to VisualBench.cpp for a couple of calls.

BUG=skia:

Review URL: https://codereview.chromium.org/1304083007
diff --git a/tools/VisualBench/VisualLightweightBenchModule.cpp b/tools/VisualBench/VisualLightweightBenchModule.cpp
new file mode 100644
index 0000000..8f9e488
--- /dev/null
+++ b/tools/VisualBench/VisualLightweightBenchModule.cpp
@@ -0,0 +1,256 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ *
+ */
+
+#include "VisualLightweightBenchModule.h"
+
+#include "ProcStats.h"
+#include "SkApplication.h"
+#include "SkCanvas.h"
+#include "SkCommandLineFlags.h"
+#include "SkForceLinking.h"
+#include "SkGraphics.h"
+#include "SkGr.h"
+#include "SkImageDecoder.h"
+#include "SkOSFile.h"
+#include "SkStream.h"
+#include "Stats.h"
+#include "gl/GrGLInterface.h"
+
+__SK_FORCE_IMAGE_DECODER_LINKING;
+
+// Between samples we reset context
+// Between frames we swap buffers
+
+DEFINE_int32(gpuFrameLag, 5, "Overestimate of maximum number of frames GPU allows to lag.");
+DEFINE_int32(samples, 10, "Number of times to time each skp.");
+DEFINE_int32(frames, 5, "Number of frames of each skp to render per sample.");
+DEFINE_double(loopMs, 5, "Target loop time in millseconds.");
+DEFINE_bool2(verbose, v, false, "enable verbose output from the test driver.");
+DEFINE_string(key, "", "");  // dummy to enable gm tests that have platform-specific names
+DEFINE_string(outResultsFile, "", "If given, write results here as JSON.");
+DEFINE_string(properties, "",
+              "Space-separated key/value pairs to add to JSON identifying this run.");
+
+static SkString humanize(double ms) {
+    if (FLAGS_verbose) {
+        return SkStringPrintf("%llu", (uint64_t)(ms*1e6));
+    }
+    return HumanizeMs(ms);
+}
+
+#define HUMANIZE(time) humanize(time).c_str()
+
+VisualLightweightBenchModule::VisualLightweightBenchModule(VisualBench* owner)
+    : fCurrentSample(0)
+    , fCurrentFrame(0)
+    , fLoops(1)
+    , fState(kPreWarmLoops_State)
+    , fBenchmark(nullptr)
+    , fOwner(SkRef(owner))
+    , fResults(new ResultsWriter) {
+    fBenchmarkStream.reset(new VisualBenchmarkStream);
+
+    // Print header
+    SkDebugf("curr/maxrss\tloops\tflushes\tmin\tmedian\tmean\tmax\tstddev\tbench\n");
+
+    // setup json logging if required
+    if (!FLAGS_outResultsFile.isEmpty()) {
+        fResults.reset(new NanoJSONResultsWriter(FLAGS_outResultsFile[0]));
+    }
+
+    if (1 == FLAGS_properties.count() % 2) {
+        SkDebugf("ERROR: --properties must be passed with an even number of arguments.\n");
+    } else {
+        for (int i = 1; i < FLAGS_properties.count(); i += 2) {
+            fResults->property(FLAGS_properties[i - 1], FLAGS_properties[i]);
+        }
+    }
+}
+
+inline void VisualLightweightBenchModule::renderFrame(SkCanvas* canvas) {
+    fBenchmark->draw(fLoops, canvas);
+    canvas->flush();
+    fOwner->present();
+}
+
+void VisualLightweightBenchModule::printStats() {
+    const SkTArray<double>& measurements = fRecords.back().fMeasurements;
+    const char* shortName = fBenchmark->getUniqueName();
+
+    // update log
+    // Note: We currently log only the minimum.  It would be interesting to log more information
+    SkString configName;
+    if (FLAGS_msaa > 0) {
+        configName.appendf("msaa_%d", FLAGS_msaa);
+    } else {
+        configName.appendf("gpu");
+    }
+    fResults->config(configName.c_str());
+    fResults->configOption("name", fBenchmark->getUniqueName());
+    SkASSERT(measurements.count());
+    Stats stats(measurements);
+    fResults->metric("min_ms",    stats.min);
+
+    // Print output
+    if (FLAGS_verbose) {
+        for (int i = 0; i < measurements.count(); i++) {
+            SkDebugf("%s  ", HUMANIZE(measurements[i]));
+        }
+        SkDebugf("%s\n", shortName);
+    } else {
+        const double stdDevPercent = 100 * sqrt(stats.var) / stats.mean;
+        SkDebugf("%4d/%-4dMB\t%d\t%s\t%s\t%s\t%s\t%.0f%%\t%s\n",
+                 sk_tools::getCurrResidentSetSizeMB(),
+                 sk_tools::getMaxResidentSetSizeMB(),
+                 fLoops,
+                 HUMANIZE(stats.min),
+                 HUMANIZE(stats.median),
+                 HUMANIZE(stats.mean),
+                 HUMANIZE(stats.max),
+                 stdDevPercent,
+                 shortName);
+    }
+}
+
+bool VisualLightweightBenchModule::advanceRecordIfNecessary(SkCanvas* canvas) {
+    if (fBenchmark) {
+        return true;
+    }
+
+    fBenchmark.reset(fBenchmarkStream->next());
+    if (!fBenchmark) {
+        return false;
+    }
+
+    canvas->clear(0xffffffff);
+    fBenchmark->preDraw();
+    fRecords.push_back();
+
+    // Log bench name
+    fResults->bench(fBenchmark->getUniqueName(), fBenchmark->getSize().fX,
+                    fBenchmark->getSize().fY);
+    return true;
+}
+
+inline void VisualLightweightBenchModule::nextState(State nextState) {
+    fState = nextState;
+}
+
+void VisualLightweightBenchModule::perCanvasPreDraw(SkCanvas* canvas, State nextState) {
+    fBenchmark->perCanvasPreDraw(canvas);
+    fCurrentFrame = 0;
+    this->nextState(nextState);
+}
+
+void VisualLightweightBenchModule::preWarm(State nextState) {
+    if (fCurrentFrame >= FLAGS_gpuFrameLag) {
+        // we currently time across all frames to make sure we capture all GPU work
+        this->nextState(nextState);
+        fCurrentFrame = 0;
+        fTimer.start();
+    } else {
+        fCurrentFrame++;
+    }
+}
+
+void VisualLightweightBenchModule::draw(SkCanvas* canvas) {
+    if (!this->advanceRecordIfNecessary(canvas)) {
+        SkDebugf("Exiting VisualBench successfully\n");
+        fOwner->closeWindow();
+        return;
+    }
+    this->renderFrame(canvas);
+    switch (fState) {
+        case kPreWarmLoopsPerCanvasPreDraw_State: {
+            this->perCanvasPreDraw(canvas, kPreWarmLoops_State);
+            break;
+        }
+        case kPreWarmLoops_State: {
+            this->preWarm(kTuneLoops_State);
+            break;
+        }
+        case kTuneLoops_State: {
+            this->tuneLoops();
+            break;
+        }
+        case kPreWarmTimingPerCanvasPreDraw_State: {
+            this->perCanvasPreDraw(canvas, kPreWarmTiming_State);
+            break;
+        }
+        case kPreWarmTiming_State: {
+            this->preWarm(kTiming_State);
+            break;
+        }
+        case kTiming_State: {
+            this->timing(canvas);
+            break;
+        }
+    }
+}
+
+inline double VisualLightweightBenchModule::elapsed() {
+    fTimer.end();
+    return fTimer.fWall;
+}
+
+void VisualLightweightBenchModule::resetTimingState() {
+    fCurrentFrame = 0;
+    fTimer = WallTimer();
+    fOwner->reset();
+}
+
+void VisualLightweightBenchModule::scaleLoops(double elapsedMs) {
+    // Scale back the number of loops
+    fLoops = (int)ceil(fLoops * FLAGS_loopMs / elapsedMs);
+}
+
+inline void VisualLightweightBenchModule::tuneLoops() {
+    if (1 << 30 == fLoops) {
+        // We're about to wrap.  Something's wrong with the bench.
+        SkDebugf("InnerLoops wrapped\n");
+        fLoops = 0;
+    } else {
+        double elapsedMs = this->elapsed();
+        if (elapsedMs > FLAGS_loopMs) {
+            this->scaleLoops(elapsedMs);
+            this->nextState(kPreWarmTimingPerCanvasPreDraw_State);
+        } else {
+            fLoops *= 2;
+            this->nextState(kPreWarmLoops_State);
+        }
+        this->resetTimingState();
+    }
+}
+
+void VisualLightweightBenchModule::recordMeasurement() {
+    double measurement = this->elapsed() / (FLAGS_frames * fLoops);
+    fRecords.back().fMeasurements.push_back(measurement);
+}
+
+void VisualLightweightBenchModule::postDraw(SkCanvas* canvas) {
+    fBenchmark->perCanvasPostDraw(canvas);
+    fBenchmark.reset(nullptr);
+    fCurrentSample = 0;
+    fLoops = 1;
+}
+
+inline void VisualLightweightBenchModule::timing(SkCanvas* canvas) {
+    if (fCurrentFrame >= FLAGS_frames) {
+        this->recordMeasurement();
+        if (fCurrentSample++ >= FLAGS_samples) {
+            this->printStats();
+            this->postDraw(canvas);
+            this->nextState(kPreWarmLoopsPerCanvasPreDraw_State);
+        } else {
+            this->nextState(kPreWarmTimingPerCanvasPreDraw_State);
+        }
+        this->resetTimingState();
+    } else {
+        fCurrentFrame++;
+    }
+}