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/base/SkThreadAnnotations.h" 10 11 #if 0 12 #include "include/private/base/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, std::size(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 debug_trace()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> do_pause()36 static void do_pause() { _mm_pause(); } 37 #else do_pause()38 static void do_pause() { /*spin*/ } 39 #endif 40 contendedAcquire()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