1 files changed, 143 insertions, 0 deletions
diff --git a/storage/SQLiteMutex.h b/storage/SQLiteMutex.h
new file mode 100644
index 0000000000..b7198b1912
--- /dev/null
+++ b/storage/SQLiteMutex.h
@@ -0,0 +1,143 @@
+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_storage_SQLiteMutex_h_
+#define mozilla_storage_SQLiteMutex_h_
+
+#include "mozilla/BlockingResourceBase.h"
+#include "sqlite3.h"
+
+namespace mozilla {
+namespace storage {
+
+/**
+ * Wrapper class for sqlite3_mutexes.  To be used whenever we want to use a
+ * sqlite3_mutex.
+ *
+ * @warning Never EVER wrap the same sqlite3_mutex with a different SQLiteMutex.
+ *          If you do this, you void the deadlock detector's warranty!
+ */
+class SQLiteMutex : private BlockingResourceBase {
+ public:
+  /**
+   * Constructs a wrapper for a sqlite3_mutex that has deadlock detecting.
+   *
+   * @param aName
+   *        A name which can be used to reference this mutex.
+   */
+  explicit SQLiteMutex(const char* aName)
+      : BlockingResourceBase(aName, eMutex), mMutex(nullptr) {}
+
+  /**
+   * Sets the mutex that we are wrapping.  We generally do not have access to
+   * our mutex at class construction, so we have to set it once we get access to
+   * it.
+   *
+   * @param aMutex
+   *        The sqlite3_mutex that we are going to wrap.
+   */
+  void initWithMutex(sqlite3_mutex* aMutex) {
+    MOZ_ASSERT(aMutex, "You must pass in a valid mutex!");
+    MOZ_ASSERT(!mMutex, "A mutex has already been set for this!");
+    mMutex = aMutex;
+  }
+
+  /**
+   * After a connection has been successfully closed, its mutex is a dangling
+   * pointer, and as such it should be destroyed.
+   */
+  void destroy() { mMutex = NULL; }
+
+  /**
+   * Acquires the mutex.
+   */
+  void lock() {
+    MOZ_ASSERT(mMutex, "No mutex associated with this wrapper!");
+#if defined(DEBUG)
+    // While SQLite Mutexes may be recursive, in our own code we do not want to
+    // treat them as such.
+    CheckAcquire();
+#endif
+
+    ::sqlite3_mutex_enter(mMutex);
+
+#if defined(DEBUG)
+    Acquire();  // Call is protected by us holding the mutex.
+#endif
+  }
+
+  /**
+   * Releases the mutex.
+   */
+  void unlock() {
+    MOZ_ASSERT(mMutex, "No mutex associated with this wrapper!");
+#if defined(DEBUG)
+    // While SQLite Mutexes may be recursive, in our own code we do not want to
+    // treat them as such.
+    Release();  // Call is protected by us holding the mutex.
+#endif
+
+    ::sqlite3_mutex_leave(mMutex);
+  }
+
+  /**
+   * Asserts that the current thread owns the mutex.
+   */
+  void assertCurrentThreadOwns() {
+    MOZ_ASSERT(mMutex, "No mutex associated with this wrapper!");
+    MOZ_ASSERT(::sqlite3_mutex_held(mMutex),
+               "Mutex is not held, but we expect it to be!");
+  }
+
+  /**
+   * Asserts that the current thread does not own the mutex.
+   */
+  void assertNotCurrentThreadOwns() {
+    MOZ_ASSERT(mMutex, "No mutex associated with this wrapper!");
+    MOZ_ASSERT(::sqlite3_mutex_notheld(mMutex),
+               "Mutex is held, but we expect it to not be!");
+  }
+
+ private:
+  sqlite3_mutex* mMutex;
+};
+
+/**
+ * Automatically acquires the mutex when it enters scope, and releases it when
+ * it leaves scope.
+ */
+class MOZ_STACK_CLASS SQLiteMutexAutoLock {
+ public:
+  explicit SQLiteMutexAutoLock(SQLiteMutex& aMutex) : mMutex(aMutex) {
+    mMutex.lock();
+  }
+
+  ~SQLiteMutexAutoLock() { mMutex.unlock(); }
+
+ private:
+  SQLiteMutex& mMutex;
+};
+
+/**
+ * Automatically releases the mutex when it enters scope, and acquires it when
+ * it leaves scope.
+ */
+class MOZ_STACK_CLASS SQLiteMutexAutoUnlock {
+ public:
+  explicit SQLiteMutexAutoUnlock(SQLiteMutex& aMutex) : mMutex(aMutex) {
+    mMutex.unlock();
+  }
+
+  ~SQLiteMutexAutoUnlock() { mMutex.lock(); }
+
+ private:
+  SQLiteMutex& mMutex;
+};
+
+}  // namespace storage
+}  // namespace mozilla
+
+#endif  // mozilla_storage_SQLiteMutex_h_