1 files changed, 237 insertions, 0 deletions
diff --git a/image/test/gtest/TestCopyOnWrite.cpp b/image/test/gtest/TestCopyOnWrite.cpp
new file mode 100644
index 0000000000..d5ad3e4f6b
--- /dev/null
+++ b/image/test/gtest/TestCopyOnWrite.cpp
@@ -0,0 +1,237 @@
+/* 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/. */
+
+#include "gtest/gtest.h"
+
+#include "CopyOnWrite.h"
+
+using namespace mozilla;
+using namespace mozilla::image;
+
+struct ValueStats {
+  int32_t mCopies = 0;
+  int32_t mFrees = 0;
+  int32_t mCalls = 0;
+  int32_t mConstCalls = 0;
+  int32_t mSerial = 0;
+};
+
+struct Value {
+  NS_INLINE_DECL_REFCOUNTING(Value)
+
+  explicit Value(ValueStats& aStats)
+      : mStats(aStats), mSerial(mStats.mSerial++) {}
+
+  Value(const Value& aOther)
+      : mStats(aOther.mStats), mSerial(mStats.mSerial++) {
+    mStats.mCopies++;
+  }
+
+  void Go() { mStats.mCalls++; }
+  void Go() const { mStats.mConstCalls++; }
+
+  int32_t Serial() const { return mSerial; }
+
+ protected:
+  ~Value() { mStats.mFrees++; }
+
+ private:
+  ValueStats& mStats;
+  int32_t mSerial;
+};
+
+TEST(ImageCopyOnWrite, Read)
+{
+  ValueStats stats;
+
+  {
+    CopyOnWrite<Value> cow(new Value(stats));
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_TRUE(cow.CanRead());
+
+    cow.Read([&](const Value* aValue) {
+      EXPECT_EQ(0, stats.mCopies);
+      EXPECT_EQ(0, stats.mFrees);
+      EXPECT_EQ(0, aValue->Serial());
+      EXPECT_TRUE(cow.CanRead());
+      EXPECT_TRUE(cow.CanWrite());
+
+      aValue->Go();
+
+      EXPECT_EQ(0, stats.mCalls);
+      EXPECT_EQ(1, stats.mConstCalls);
+    });
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_EQ(0, stats.mCalls);
+    EXPECT_EQ(1, stats.mConstCalls);
+  }
+
+  EXPECT_EQ(0, stats.mCopies);
+  EXPECT_EQ(1, stats.mFrees);
+}
+
+TEST(ImageCopyOnWrite, RecursiveRead)
+{
+  ValueStats stats;
+
+  {
+    CopyOnWrite<Value> cow(new Value(stats));
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_TRUE(cow.CanRead());
+
+    cow.Read([&](const Value* aValue) {
+      EXPECT_EQ(0, stats.mCopies);
+      EXPECT_EQ(0, stats.mFrees);
+      EXPECT_EQ(0, aValue->Serial());
+      EXPECT_TRUE(cow.CanRead());
+      EXPECT_TRUE(cow.CanWrite());
+
+      // Make sure that Read() inside a Read() succeeds.
+      cow.Read(
+          [&](const Value* aValue) {
+            EXPECT_EQ(0, stats.mCopies);
+            EXPECT_EQ(0, stats.mFrees);
+            EXPECT_EQ(0, aValue->Serial());
+            EXPECT_TRUE(cow.CanRead());
+            EXPECT_TRUE(cow.CanWrite());
+
+            aValue->Go();
+
+            EXPECT_EQ(0, stats.mCalls);
+            EXPECT_EQ(1, stats.mConstCalls);
+          },
+          []() {
+            // This gets called if we can't read. We shouldn't get here.
+            EXPECT_TRUE(false);
+          });
+    });
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_EQ(0, stats.mCalls);
+    EXPECT_EQ(1, stats.mConstCalls);
+  }
+
+  EXPECT_EQ(0, stats.mCopies);
+  EXPECT_EQ(1, stats.mFrees);
+}
+
+TEST(ImageCopyOnWrite, Write)
+{
+  ValueStats stats;
+
+  {
+    CopyOnWrite<Value> cow(new Value(stats));
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_TRUE(cow.CanRead());
+    EXPECT_TRUE(cow.CanWrite());
+
+    cow.Write([&](Value* aValue) {
+      EXPECT_EQ(0, stats.mCopies);
+      EXPECT_EQ(0, stats.mFrees);
+      EXPECT_EQ(0, aValue->Serial());
+      EXPECT_TRUE(!cow.CanRead());
+      EXPECT_TRUE(!cow.CanWrite());
+
+      aValue->Go();
+
+      EXPECT_EQ(1, stats.mCalls);
+      EXPECT_EQ(0, stats.mConstCalls);
+    });
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_EQ(1, stats.mCalls);
+    EXPECT_EQ(0, stats.mConstCalls);
+  }
+
+  EXPECT_EQ(0, stats.mCopies);
+  EXPECT_EQ(1, stats.mFrees);
+}
+
+TEST(ImageCopyOnWrite, WriteRecursive)
+{
+  ValueStats stats;
+
+  {
+    CopyOnWrite<Value> cow(new Value(stats));
+
+    EXPECT_EQ(0, stats.mCopies);
+    EXPECT_EQ(0, stats.mFrees);
+    EXPECT_TRUE(cow.CanRead());
+    EXPECT_TRUE(cow.CanWrite());
+
+    cow.Read([&](const Value* aValue) {
+      EXPECT_EQ(0, stats.mCopies);
+      EXPECT_EQ(0, stats.mFrees);
+      EXPECT_EQ(0, aValue->Serial());
+      EXPECT_TRUE(cow.CanRead());
+      EXPECT_TRUE(cow.CanWrite());
+
+      // Make sure Write() inside a Read() succeeds.
+      cow.Write(
+          [&](Value* aValue) {
+            EXPECT_EQ(1, stats.mCopies);
+            EXPECT_EQ(0, stats.mFrees);
+            EXPECT_EQ(1, aValue->Serial());
+            EXPECT_TRUE(!cow.CanRead());
+            EXPECT_TRUE(!cow.CanWrite());
+
+            aValue->Go();
+
+            EXPECT_EQ(1, stats.mCalls);
+            EXPECT_EQ(0, stats.mConstCalls);
+
+            // Make sure Read() inside a Write() fails.
+            cow.Read(
+                [](const Value* aValue) {
+                  // This gets called if we can read. We shouldn't get here.
+                  EXPECT_TRUE(false);
+                },
+                []() {
+                  // This gets called if we can't read. We *should* get here.
+                  EXPECT_TRUE(true);
+                });
+
+            // Make sure Write() inside a Write() fails.
+            cow.Write(
+                [](Value* aValue) {
+                  // This gets called if we can write. We shouldn't get here.
+                  EXPECT_TRUE(false);
+                },
+                []() {
+                  // This gets called if we can't write. We *should* get here.
+                  EXPECT_TRUE(true);
+                });
+          },
+          []() {
+            // This gets called if we can't write. We shouldn't get here.
+            EXPECT_TRUE(false);
+          });
+
+      aValue->Go();
+
+      EXPECT_EQ(1, stats.mCopies);
+      EXPECT_EQ(0, stats.mFrees);
+      EXPECT_EQ(1, stats.mCalls);
+      EXPECT_EQ(1, stats.mConstCalls);
+    });
+
+    EXPECT_EQ(1, stats.mCopies);
+    EXPECT_EQ(1, stats.mFrees);
+    EXPECT_EQ(1, stats.mCalls);
+    EXPECT_EQ(1, stats.mConstCalls);
+  }
+
+  EXPECT_EQ(1, stats.mCopies);
+  EXPECT_EQ(2, stats.mFrees);
+}