add experimental tls (for font cache eventually)

git-svn-id: http://skia.googlecode.com/svn/trunk@3748 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 116 insertions, 0 deletions

diff --git a/src/core/SkTLS.h b/src/core/SkTLS.h
new file mode 100644
index 0000000000..86886f0080
--- /dev/null
+++ b/src/core/SkTLS.h
@@ -0,0 +1,36 @@
+//
+//  SkTLS.h
+//  
+//
+//  Created by Mike Reed on 4/21/12.
+//  Copyright (c) 2012 __MyCompanyName__. All rights reserved.
+//
+
+#ifndef SkTLS_DEFINED
+#define SkTLS_DEFINED
+
+#include "SkTypes.h"
+
+class SkTLS {
+public:
+    typedef void* (*CreateProc)();
+    typedef void  (*DeleteProc)(void*);
+
+    /**
+     *  Create proc is called once per thread, and its return value is cached
+     *  and returned by this call, treating the proc as a key. When this thread
+     *  exists, if DeleteProc is not NULL, it is called and passed the value
+     *  that was returned by CreateProc.
+     */
+    static void* Get(CreateProc, DeleteProc);
+
+    /**
+     *  If Get() has previously been called with this CreateProc, then this
+     *  returns its cached data, otherwise it returns NULL. The CreateProc is
+     *  never invoked in Find, it is only used as a key for searching the
+     *  cache.
+     */
+    static void* Find(CreateProc);
+};
+
+#endif
diff --git a/src/ports/SkThread_pthread.cpp b/src/ports/SkThread_pthread.cpp
index 4750d4f2c4..87606e2ca7 100644
--- a/src/ports/SkThread_pthread.cpp
+++ b/src/ports/SkThread_pthread.cpp
@@ -149,3 +149,83 @@ void SkMutex::release() {
 }
 
 #endif // !SK_USE_POSIX_THREADS
+
+///////////////////////////////////////////////////////////////////////////////
+
+#include "SkTLS.h"
+
+struct SkTLSRec {
+    SkTLSRec*           fNext;
+    void*               fData;
+    SkTLS::CreateProc   fCreateProc;
+    SkTLS::DeleteProc   fDeleteProc;
+};
+
+static void sk_tls_destructor(void* ptr) {
+    SkTLSRec* rec = (SkTLSRec*)ptr;
+    do {
+        SkTLSRec* next = rec->fNext;
+        if (rec->fDeleteProc) {
+            rec->fDeleteProc(rec->fData);
+        }
+        delete rec;
+        rec = next;
+    } while (NULL != rec);
+}
+
+static pthread_key_t gSkTLSKey;
+static pthread_once_t gSkTLSKey_Once = PTHREAD_ONCE_INIT;
+
+static void sk_tls_make_key() {
+    (void)pthread_key_create(&gSkTLSKey, sk_tls_destructor);
+}
+
+void* SkTLS::Get(CreateProc createProc, DeleteProc deleteProc) {
+    if (NULL == createProc) {
+        return NULL;
+    }
+
+    (void)pthread_once(&gSkTLSKey_Once, sk_tls_make_key);
+    void* ptr = pthread_getspecific(gSkTLSKey);
+
+    if (ptr) {
+        const SkTLSRec* rec = (const SkTLSRec*)ptr;
+        do {
+            if (rec->fCreateProc == createProc) {
+                SkASSERT(rec->fDeleteProc == deleteProc);
+                return rec->fData;
+            }
+        } while ((rec = rec->fNext) != NULL);
+        // not found, so create a new one
+    }
+    
+    // add a new head of our change
+    SkTLSRec* rec = new SkTLSRec;
+    rec->fNext = (SkTLSRec*)ptr;
+    (void)pthread_setspecific(gSkTLSKey, rec);
+
+    rec->fData = createProc();
+    rec->fCreateProc = createProc;
+    rec->fDeleteProc = deleteProc;
+    return rec->fData;
+}
+
+void* SkTLS::Find(CreateProc createProc) {
+    if (NULL == createProc) {
+        return NULL;
+    }
+    
+    (void)pthread_once(&gSkTLSKey_Once, sk_tls_make_key);
+    void* ptr = pthread_getspecific(gSkTLSKey);
+
+    if (ptr) {
+        const SkTLSRec* rec = (const SkTLSRec*)ptr;
+        do {
+            if (rec->fCreateProc == createProc) {
+                return rec->fData;
+            }
+        } while ((rec = rec->fNext) != NULL);
+    }
+    return NULL;
+}
+