Create a thermal manager class and wire it in to nanobench behind a flag

tools/ThermalManager.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef ThermalManager_DEFINED
+#define ThermalManager_DEFINED
+
+#include "SkString.h"
+#include "SkTArray.h"
+
+#define USE_THERMAL_MANAGER defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)

[djsollen, 2016/02/05 04:54:15]

It would be more clear to me if you wrote it something like...

#if defined(SK_BUILD_FOR_ANDROID) || defined(SK_BUILD_FOR_UNIX)
#    define THERMAL_MANAGER_SUPPORTED
#endif

[joshualitt, 2016/02/05 13:50:20]

Acknowledged.

[joshualitt, 2016/02/05 13:50:20]

Acknowledged.

[mtklein, 2016/02/05 13:54:21]

More than that, Derek's version is legal preprocessor.  The version written here
doesn't necessarily work.  defined and !defined go in #if and #elif only.

+
+#if USE_THERMAL_MANAGER
+
+/*
+ * This simple class monitors the thermal part of sysfs to ensure we don't trigger thermal events
+ */
+
+class ThermalManager {
+public:
+    ThermalManager(int32_t threshold = 1);
+
+    bool coolOffIfNecessary(uint32_t sleepInterval = 10, uint32_t maxSleeps = 1000);

[djsollen, 2016/02/05 04:54:15]

can you document that the sleep interval is in seconds, ms, ns?  Also I think it
is more clear to have a timeout value instead of maxSleeps, since the latter
requires me to do the math in my head each time to get the timeout value (which
to me is the number I care about).

[joshualitt, 2016/02/05 13:50:20]

Acknowledged.

+
+private:
+    static int32_t OpenFileAndReadInt32(const char* path);
+
+    static int32_t GetTemp(SkString thermalZonePath) {
+        SkString temperatureFilePath(thermalZonePath);
+        temperatureFilePath.appendf("/temp");
+        return OpenFileAndReadInt32(temperatureFilePath.c_str());
+    }
+
+    struct TripPoint {
+        TripPoint(SkString thermalZoneRoot, SkString pointName, int32_t threshold);
+
+        bool willTrip();
+
+        SkString fThermalZoneRoot;
+        SkString fPointName;
+        int32_t fBase;
+        int32_t fPoint;
+        int32_t fThreshold;
+        bool fDisabled;
+    };
+
+    SkTArray<TripPoint> fTripPoints;
+};
+#endif
+#endif