1/* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8#include "include/private/SkSpinlock.h" 9#include "include/private/SkThreadAnnotations.h" 10 11#if 0 12 #include "include/private/SkMutex.h" 13 #include <execinfo.h> 14 #include <stdio.h> 15 16 static void debug_trace() { 17 void* stack[64]; 18 int len = backtrace(stack, SK_ARRAY_COUNT(stack)); 19 20 // As you might imagine, we can't use an SkSpinlock here... 21 static SkMutex lock; 22 { 23 SkAutoMutexExclusive locked(lock); 24 fprintf(stderr, "\n"); 25 backtrace_symbols_fd(stack, len, 2/*stderr*/); 26 fprintf(stderr, "\n"); 27 } 28 } 29#else 30 static void debug_trace() {} 31#endif 32 33// Renamed from "pause" to avoid conflict with function defined in unistd.h 34#if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 35 #include <emmintrin.h> 36 static void do_pause() { _mm_pause(); } 37#else 38 static void do_pause() { /*spin*/ } 39#endif 40 41void SkSpinlock::contendedAcquire() { 42 debug_trace(); 43 44 // To act as a mutex, we need an acquire barrier when we acquire the lock. 45 SK_POTENTIALLY_BLOCKING_REGION_BEGIN; 46 while (fLocked.exchange(true, std::memory_order_acquire)) { 47 do_pause(); 48 } 49 SK_POTENTIALLY_BLOCKING_REGION_END; 50} 51