libsanitizer/tsan/tsan_mutexset.cpp

   1 //===-- tsan_mutexset.cpp -------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of ThreadSanitizer (TSan), a race detector.
  10 //
  11 //===----------------------------------------------------------------------===//
  12 #include "tsan_mutexset.h"
  13 #include "tsan_rtl.h"
  14
  15 namespace __tsan {
  16
  17 const uptr MutexSet::kMaxSize;
  18
  19 MutexSet::MutexSet() {
  20   size_ = 0;
  21   internal_memset(&descs_, 0, sizeof(descs_));
  22 }
  23
  24 void MutexSet::Add(u64 id, bool write, u64 epoch) {
  25   // Look up existing mutex with the same id.
  26   for (uptr i = 0; i < size_; i++) {
  27     if (descs_[i].id == id) {
  28       descs_[i].count++;
  29       descs_[i].epoch = epoch;
  30       return;
  31     }
  32   }
  33   // On overflow, find the oldest mutex and drop it.
  34   if (size_ == kMaxSize) {
  35     u64 minepoch = (u64)-1;
  36     u64 mini = (u64)-1;
  37     for (uptr i = 0; i < size_; i++) {
  38       if (descs_[i].epoch < minepoch) {
  39         minepoch = descs_[i].epoch;
  40         mini = i;
  41       }
  42     }
  43     RemovePos(mini);
  44     CHECK_EQ(size_, kMaxSize - 1);
  45   }
  46   // Add new mutex descriptor.
  47   descs_[size_].id = id;
  48   descs_[size_].write = write;
  49   descs_[size_].epoch = epoch;
  50   descs_[size_].count = 1;
  51   size_++;
  52 }
  53
  54 void MutexSet::Del(u64 id, bool write) {
  55   for (uptr i = 0; i < size_; i++) {
  56     if (descs_[i].id == id) {
  57       if (--descs_[i].count == 0)
  58         RemovePos(i);
  59       return;
  60     }
  61   }
  62 }
  63
  64 void MutexSet::Remove(u64 id) {
  65   for (uptr i = 0; i < size_; i++) {
  66     if (descs_[i].id == id) {
  67       RemovePos(i);
  68       return;
  69     }
  70   }
  71 }
  72
  73 void MutexSet::RemovePos(uptr i) {
  74   CHECK_LT(i, size_);
  75   descs_[i] = descs_[size_ - 1];
  76   size_--;
  77 }
  78
  79 uptr MutexSet::Size() const {
  80   return size_;
  81 }
  82
  83 MutexSet::Desc MutexSet::Get(uptr i) const {
  84   CHECK_LT(i, size_);
  85   return descs_[i];
  86 }
  87
  88 }  // namespace __tsan