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 "src/base/SkSpinlock.h" 9 10 #include "include/private/base/SkFeatures.h" 11 #include "include/private/base/SkThreadAnnotations.h" 12 13 #if 0 14 #include "include/private/base/SkMutex.h" 15 #include <execinfo.h> 16 #include <stdio.h> 17 18 static void debug_trace() { 19 void* stack[64]; 20 int len = backtrace(stack, std::size(stack)); 21 22 // As you might imagine, we can't use an SkSpinlock here... 23 static SkMutex lock; 24 { 25 SkAutoMutexExclusive locked(lock); 26 fprintf(stderr, "\n"); 27 backtrace_symbols_fd(stack, len, 2/*stderr*/); 28 fprintf(stderr, "\n"); 29 } 30 } 31 #else debug_trace()32 static void debug_trace() {} 33 #endif 34 35 // Renamed from "pause" to avoid conflict with function defined in unistd.h 36 #if SK_CPU_SSE_LEVEL >= SK_CPU_SSE_LEVEL_SSE2 37 #include <emmintrin.h> do_pause()38 static void do_pause() { _mm_pause(); } 39 #else do_pause()40 static void do_pause() { /*spin*/ } 41 #endif 42 contendedAcquire()43void SkSpinlock::contendedAcquire() { 44 debug_trace(); 45 46 // To act as a mutex, we need an acquire barrier when we acquire the lock. 47 SK_POTENTIALLY_BLOCKING_REGION_BEGIN; 48 while (fLocked.exchange(true, std::memory_order_acquire)) { 49 do_pause(); 50 } 51 SK_POTENTIALLY_BLOCKING_REGION_END; 52 } 53