Better refcounting and locking

All major externally accessible objects (especially FontFamily and
FontCollection) are now reference counted. In addition, there is a
global lock intended to make operations thread-safe.

WIP notice: in this version of the patch, not all external API entry
points are protected by the lock. That should be fixed.

Change-Id: I14106196e99eb101e8bf1bcb4b81359759d2086c

4 files changed, 56 insertions, 22 deletions

diff --git a/include/minikin/FontCollection.h b/include/minikin/FontCollection.h
index a2a5391..dc48f8e 100644
--- a/include/minikin/FontCollection.h
+++ b/include/minikin/FontCollection.h
@@ -19,13 +19,14 @@
 
 #include <vector>
 
+#include <minikin/MinikinRefCounted.h>
 #include <minikin/MinikinFont.h>
 #include <minikin/SparseBitSet.h>
 #include <minikin/FontFamily.h>
 
 namespace android {
 
-class FontCollection {
+class FontCollection : public MinikinRefCounted {
 public:
     explicit FontCollection(const std::vector<FontFamily*>& typefaces);
 
@@ -37,17 +38,17 @@ public:
         // Do copy constructor, assignment, destructor so it can be used in vectors
         Run() : font(NULL) { }
         Run(const Run& other): font(other.font), start(other.start), end(other.end) {
-            if (font) font->Ref();
+            if (font) font->RefLocked();
         }
         Run& operator=(const Run& other) {
-            if (other.font) other.font->Ref();
-            if (font) font->Unref();
+            if (other.font) other.font->RefLocked();
+            if (font) font->UnrefLocked();
             font = other.font;
             start = other.start;
             end = other.end;
             return *this;
         }
-        ~Run() { if (font) font->Unref(); }
+        ~Run() { if (font) font->UnrefLocked(); }
 
         MinikinFont* font;
         int start;
diff --git a/include/minikin/FontFamily.h b/include/minikin/FontFamily.h
index 290220b..3b59017 100644
--- a/include/minikin/FontFamily.h
+++ b/include/minikin/FontFamily.h
@@ -19,6 +19,8 @@
 
 #include <vector>
 
+#include <minikin/MinikinRefCounted.h>
+
 namespace android {
 
 // FontStyle represents all style information needed to select an actual font
@@ -39,8 +41,10 @@ private:
     uint32_t bits;
 };
 
-class FontFamily {
+class FontFamily : public MinikinRefCounted {
 public:
+    ~FontFamily();
+
     // Add font to family, extracting style information from the font
     bool addFont(MinikinFont* typeface);
 
diff --git a/include/minikin/MinikinFont.h b/include/minikin/MinikinFont.h
index e84f5df..568f19d 100644
--- a/include/minikin/MinikinFont.h
+++ b/include/minikin/MinikinFont.h
@@ -17,6 +17,8 @@
 #ifndef MINIKIN_FONT_H
 #define MINIKIN_FONT_H
 
+#include <minikin/MinikinRefCounted.h>
+
 // An abstraction for platform fonts, allowing Minikin to be used with
 // multiple actual implementations of fonts.
 
@@ -56,15 +58,8 @@ struct MinikinRect {
 
 class MinikinFontFreeType;
 
-class MinikinFont {
+class MinikinFont : public MinikinRefCounted {
 public:
-    void Ref() { mRefcount_++; }
-    void Unref() { if (--mRefcount_ == 0) { delete this; } }
-
-    MinikinFont() : mRefcount_(1) { }
-
-    virtual ~MinikinFont() { };
-
     virtual bool GetGlyph(uint32_t codepoint, uint32_t *glyph) const = 0;
 
     virtual float GetHorizontalAdvance(uint32_t glyph_id,
@@ -82,14 +77,6 @@ public:
         return ((uint32_t)c1 << 24) | ((uint32_t)c2 << 16) |
             ((uint32_t)c3 << 8) | (uint32_t)c4;
     }
-
-    // This is used to implement a downcast without RTTI
-    virtual MinikinFontFreeType* GetFreeType() {
-        return NULL;
-    }
-
-private:
-    int mRefcount_;
 };
 
 }  // namespace android
diff --git a/include/minikin/MinikinRefCounted.h b/include/minikin/MinikinRefCounted.h
new file mode 100644
index 0000000..74d27fe
--- /dev/null
+++ b/include/minikin/MinikinRefCounted.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2014 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// Base class for reference counted objects in Minikin
+
+#ifndef MINIKIN_REF_COUNTED_H
+#define MINIKIN_REF_COUNTED_H
+
+namespace android {
+
+class MinikinRefCounted {
+public:
+    void RefLocked() { mRefcount_++; }
+    void UnrefLocked() { if (--mRefcount_ == 0) { delete this; } }
+
+    // These refcount operations take the global lock.
+    void Ref();
+    void Unref();
+
+    MinikinRefCounted() : mRefcount_(1) { }
+
+    virtual ~MinikinRefCounted() { };
+private:
+    int mRefcount_;
+};
+
+}
+
+#endif   // MINIKIN_REF_COUNTED_H
\ No newline at end of file