From e9e0dea15b4d806f5da19ffa8135d4a9c62a860b Mon Sep 17 00:00:00 2001
From: mtklein <mtklein@chromium.org>
Date: Tue, 21 Oct 2014 12:20:04 -0700
Subject: [PATCH] SkLazyPtr follow ups

 - moves test to LazyPtrTest.cpp
 - adds the ability to use a Create() method with an argument

BUG=skia:

Review URL: https://codereview.chromium.org/669783002
---
 gyp/tests.gypi                         |  2 +-
 src/core/SkLazyPtr.h                   | 40 +++++++++++++++++---------
 tests/{LazyPtr.cpp => LazyPtrTest.cpp} | 33 ++++++++++++++++++++-
 3 files changed, 60 insertions(+), 15 deletions(-)
 rename tests/{LazyPtr.cpp => LazyPtrTest.cpp} (50%)

diff --git a/gyp/tests.gypi b/gyp/tests.gypi
index 422a22e2ce..827d6e3a0c 100644
--- a/gyp/tests.gypi
+++ b/gyp/tests.gypi
@@ -130,7 +130,7 @@
     '../tests/LListTest.cpp',
     '../tests/LayerDrawLooperTest.cpp',
     '../tests/LayerRasterizerTest.cpp',
-    '../tests/LazyPtr.cpp',
+    '../tests/LazyPtrTest.cpp',
     '../tests/MD5Test.cpp',
     '../tests/MallocPixelRefTest.cpp',
     '../tests/MathTest.cpp',
diff --git a/src/core/SkLazyPtr.h b/src/core/SkLazyPtr.h
index f9508c5973..7273079252 100644
--- a/src/core/SkLazyPtr.h
+++ b/src/core/SkLazyPtr.h
@@ -49,10 +49,10 @@
  */
 
 #define SK_DECLARE_STATIC_LAZY_PTR(T, name, ...) \
-    namespace {} static Private::SkLazyPtrBase<T, ##__VA_ARGS__> name
+    namespace {} static Private::SkStaticLazyPtr<T, ##__VA_ARGS__> name
 
 #define SK_DECLARE_STATIC_LAZY_PTR_ARRAY(T, name, N, ...) \
-    namespace {} static Private::SkLazyPtrArray<T, N, ##__VA_ARGS__> name
+    namespace {} static Private::SkStaticLazyPtrArray<T, N, ##__VA_ARGS__> name
 
 // namespace {} forces these macros to only be legal in global scopes.  Chrome has thread-safety
 // problems with them in function-local statics because it uses -fno-threadsafe-statics, and even
@@ -102,7 +102,7 @@ template <typename T> void sk_delete(T* ptr) { SkDELETE(ptr); }
 
 // This has no constructor and must be zero-initalized (the macro above does this).
 template <typename T, T* (*Create)() = sk_new<T>, void (*Destroy)(T*) = sk_delete<T> >
-class SkLazyPtrBase {
+class SkStaticLazyPtr {
 public:
     T* get() {
         // If fPtr has already been filled, we need a consume barrier when loading it.
@@ -111,7 +111,7 @@ public:
         return ptr ? ptr : try_cas<T*, Destroy>(&fPtr, Create());
     }
 
-protected:
+private:
     void* fPtr;
 };
 
@@ -119,7 +119,7 @@ template <typename T> T* sk_new_arg(int i) { return SkNEW_ARGS(T, (i)); }
 
 // This has no constructor and must be zero-initalized (the macro above does this).
 template <typename T, int N, T* (*Create)(int) = sk_new_arg<T>, void (*Destroy)(T*) = sk_delete<T> >
-class SkLazyPtrArray {
+class SkStaticLazyPtrArray {
 public:
     T* operator[](int i) {
         SkASSERT(i >= 0 && i < N);
@@ -136,16 +136,30 @@ private:
 }  // namespace Private
 
 // This version is suitable for use as a class member.
-// It's the same as above except it has a constructor to zero itself and a destructor to clean up.
-template <typename T,
-          T* (*Create)() = Private::sk_new<T>,
-          void (*Destroy)(T*) = Private::sk_delete<T> >
-class SkLazyPtr : public Private::SkLazyPtrBase<T, Create, Destroy> {
+// It's much the same as above except:
+//   - it has a constructor to zero itself;
+//   - it has a destructor to clean up;
+//   - get() calls SkNew(T) to create the pointer;
+//   - get(functor) calls functor to create the pointer.
+template <typename T, void (*Destroy)(T*) = Private::sk_delete<T> >
+class SkLazyPtr : SkNoncopyable {
 public:
-    SkLazyPtr() { INHERITED::fPtr = NULL; }
-    ~SkLazyPtr() { if (INHERITED::fPtr) { Destroy((T*)INHERITED::fPtr); } }
+    SkLazyPtr() : fPtr(NULL) {}
+    ~SkLazyPtr() { if (fPtr) { Destroy((T*)fPtr); } }
+
+    T* get() {
+        T* ptr = (T*)sk_consume_load(&fPtr);
+        return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, SkNEW(T));
+    }
+
+    template <typename Create>
+    T* get(const Create& create) {
+        T* ptr = (T*)sk_consume_load(&fPtr);
+        return ptr ? ptr : Private::try_cas<T*, Destroy>(&fPtr, create());
+    }
+
 private:
-    typedef Private::SkLazyPtrBase<T, Create, Destroy> INHERITED;
+    void* fPtr;
 };
 
 
diff --git a/tests/LazyPtr.cpp b/tests/LazyPtrTest.cpp
similarity index 50%
rename from tests/LazyPtr.cpp
rename to tests/LazyPtrTest.cpp
index ff235e6ed3..f719c2e0bf 100644
--- a/tests/LazyPtr.cpp
+++ b/tests/LazyPtrTest.cpp
@@ -2,14 +2,45 @@
 #include "SkLazyPtr.h"
 #include "SkTaskGroup.h"
 
+namespace {
+
+struct CreateIntFromFloat {
+    CreateIntFromFloat(float val) : fVal(val) {}
+    int* operator()() const { return SkNEW_ARGS(int, ((int)fVal)); }
+    float fVal;
+};
+
+// As a template argument this must have external linkage.
+void custom_destroy(int* ptr) { *ptr = 99; }
+
+} // namespace
+
 DEF_TEST(LazyPtr, r) {
+    // Basic usage: calls SkNEW(int).
     SkLazyPtr<int> lazy;
     int* ptr = lazy.get();
-
     REPORTER_ASSERT(r, ptr);
     REPORTER_ASSERT(r, lazy.get() == ptr);
 
+    // Advanced usage: calls a functor.
+    SkLazyPtr<int> lazyFunctor;
+    int* six = lazyFunctor.get(CreateIntFromFloat(6.4f));
+    REPORTER_ASSERT(r, six);
+    REPORTER_ASSERT(r, 6 == *six);
+
+    // Just makes sure this is safe.
     SkLazyPtr<double> neverRead;
+
+    // SkLazyPtr supports custom destroy methods.
+    {
+        SkLazyPtr<int, custom_destroy> customDestroy;
+        ptr = customDestroy.get();
+        // custom_destroy called here.
+    }
+    REPORTER_ASSERT(r, ptr);
+    REPORTER_ASSERT(r, 99 == *ptr);
+    // Since custom_destroy didn't actually delete ptr, we do now.
+    SkDELETE(ptr);
 }
 
 namespace {
-- 
2.34.1