1 files changed, 214 insertions, 0 deletions
diff --git a/gfx/2d/UserData.h b/gfx/2d/UserData.h
new file mode 100644
index 0000000000..16a7db343e
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+++ b/gfx/2d/UserData.h
@@ -0,0 +1,214 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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_GFX_USERDATA_H_
+#define MOZILLA_GFX_USERDATA_H_
+
+#include <stdlib.h>
+#include "Types.h"
+#include "mozilla/Assertions.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Mutex.h"
+
+namespace mozilla {
+namespace gfx {
+
+struct UserDataKey {
+  int unused;
+};
+
+/* this class is basically a clone of the user data concept from cairo */
+class UserData {
+ public:
+  typedef void (*DestroyFunc)(void* data);
+
+  UserData() : count(0), entries(nullptr) {}
+
+  /* Attaches untyped userData associated with key. destroy is called on
+   * destruction */
+  void Add(UserDataKey* key, void* userData, DestroyFunc destroy) {
+    for (int i = 0; i < count; i++) {
+      if (key == entries[i].key) {
+        if (entries[i].destroy) {
+          entries[i].destroy(entries[i].userData);
+        }
+        entries[i].userData = userData;
+        entries[i].destroy = destroy;
+        return;
+      }
+    }
+
+    // We could keep entries in a std::vector instead of managing it by hand
+    // but that would propagate an stl dependency out which we'd rather not
+    // do (see bug 666609). Plus, the entries array is expect to stay small
+    // so doing a realloc everytime we add a new entry shouldn't be too costly
+    entries =
+        static_cast<Entry*>(realloc(entries, sizeof(Entry) * (count + 1)));
+
+    if (!entries) {
+      MOZ_CRASH("GFX: UserData::Add");
+    }
+
+    entries[count].key = key;
+    entries[count].userData = userData;
+    entries[count].destroy = destroy;
+
+    count++;
+  }
+
+  /* Remove and return user data associated with key, without destroying it */
+  void* Remove(UserDataKey* key) {
+    for (int i = 0; i < count; i++) {
+      if (key == entries[i].key) {
+        void* userData = entries[i].userData;
+        // decrement before looping so entries[i+1] doesn't read past the end:
+        --count;
+        for (; i < count; i++) {
+          entries[i] = entries[i + 1];
+        }
+        return userData;
+      }
+    }
+    return nullptr;
+  }
+
+  /* Remove and destroy a given key */
+  void RemoveAndDestroy(UserDataKey* key) {
+    for (int i = 0; i < count; i++) {
+      if (key == entries[i].key) {
+        if (entries[i].destroy) {
+          entries[i].destroy(entries[i].userData);
+        }
+        // decrement before looping so entries[i+1] doesn't read past the end:
+        --count;
+        for (; i < count; i++) {
+          entries[i] = entries[i + 1];
+        }
+      }
+    }
+  }
+
+  /* Retrives the userData for the associated key */
+  void* Get(UserDataKey* key) const {
+    for (int i = 0; i < count; i++) {
+      if (key == entries[i].key) {
+        return entries[i].userData;
+      }
+    }
+    return nullptr;
+  }
+
+  bool Has(UserDataKey* key) {
+    for (int i = 0; i < count; i++) {
+      if (key == entries[i].key) {
+        return true;
+      }
+    }
+    return false;
+  }
+
+  void Destroy() {
+    if (!entries) {
+      return;
+    }
+    for (int i = 0; i < count; i++) {
+      if (entries[i].destroy) {
+        entries[i].destroy(entries[i].userData);
+      }
+    }
+    free(entries);
+    entries = nullptr;
+    count = 0;
+  }
+
+  ~UserData() { Destroy(); }
+
+ private:
+  struct Entry {
+    const UserDataKey* key;
+    void* userData;
+    DestroyFunc destroy;
+  };
+
+  int count;
+  Entry* entries;
+};
+
+class ThreadSafeUserData {
+ protected:
+  struct LockedUserData : public UserData {
+    Mutex mLock;
+
+    LockedUserData() : mLock("LockedUserData::mLock") {}
+  };
+
+ public:
+  ~ThreadSafeUserData() {
+    if (LockedUserData* userData = mUserData.exchange(nullptr)) {
+      {
+        MutexAutoLock lock(userData->mLock);
+        userData->Destroy();
+      }
+      delete userData;
+    }
+  }
+
+  void Add(UserDataKey* key, void* value, UserData::DestroyFunc destroy) {
+    LockedUserData* userData = GetUserData();
+    MutexAutoLock lock(userData->mLock);
+    userData->Add(key, value, destroy);
+  }
+
+  void* Remove(UserDataKey* key) {
+    LockedUserData* userData = GetUserData();
+    MutexAutoLock lock(userData->mLock);
+    return userData->Remove(key);
+  }
+
+  void RemoveAndDestroy(UserDataKey* key) {
+    LockedUserData* userData = GetUserData();
+    MutexAutoLock lock(userData->mLock);
+    userData->RemoveAndDestroy(key);
+  }
+
+  void* Get(UserDataKey* key) const {
+    LockedUserData* userData = GetUserData();
+    MutexAutoLock lock(userData->mLock);
+    return userData->Get(key);
+  }
+
+  bool Has(UserDataKey* key) {
+    LockedUserData* userData = GetUserData();
+    MutexAutoLock lock(userData->mLock);
+    return userData->Has(key);
+  }
+
+ private:
+  LockedUserData* GetUserData() const {
+    LockedUserData* userData = mUserData;
+    if (!userData) {
+      userData = new LockedUserData;
+      if (!mUserData.compareExchange(nullptr, userData)) {
+        delete userData;
+        userData = mUserData;
+        MOZ_ASSERT(userData);
+      }
+    }
+    return userData;
+  }
+
+  // The Mutex class is quite large. For small, frequent classes (ScaledFont,
+  // SourceSurface, etc.) this can add a lot of memory overhead, especially if
+  // UserData is only infrequently used. To avoid this, we only allocate the
+  // LockedUserData if it is actually used. If unused, it only adds a single
+  // pointer as overhead.
+  mutable Atomic<LockedUserData*> mUserData;
+};
+
+}  // namespace gfx
+}  // namespace mozilla
+
+#endif /* MOZILLA_GFX_USERDATA_H_ */