| /* |
| * Copyright 2012 Google Inc. |
| * |
| * Use of this source code is governed by a BSD-style license that can be |
| * found in the LICENSE file. |
| */ |
| |
| #ifndef SkTLS_DEFINED |
| #define SkTLS_DEFINED |
| |
| #include "SkTypes.h" |
| |
| /** |
| * Maintains a per-thread cache, using a CreateProc as the key into that cache. |
| */ |
| class SkTLS { |
| public: |
| typedef void* (*CreateProc)(); |
| typedef void (*DeleteProc)(void*); |
| |
| /** |
| * If Get() has previously been called with this CreateProc, then this |
| * returns its cached data, otherwise it returns nullptr. The CreateProc is |
| * never invoked in Find, it is only used as a key for searching the |
| * cache. |
| */ |
| static void* Find(CreateProc); |
| |
| /** |
| * Return the cached data that was returned by the CreateProc. This proc |
| * is only called the first time Get is called, and there after it is |
| * cached (per-thread), using the CreateProc as a key to look it up. |
| * |
| * When this thread, or Delete is called, the cached data is removed, and |
| * if a DeleteProc was specified, it is passed the pointer to the cached |
| * data. |
| */ |
| static void* Get(CreateProc, DeleteProc); |
| |
| /** |
| * Remove (optionally calling the DeleteProc if it was specificed in Get) |
| * the cached data associated with this CreateProc. If no associated cached |
| * data is found, do nothing. |
| */ |
| static void Delete(CreateProc); |
| |
| private: |
| // Our implementation requires only 1 TLS slot, as we manage multiple values |
| // ourselves in a list, with the platform specific value as our head. |
| |
| /** |
| * Implemented by the platform, to return the value of our (one) slot per-thread |
| * |
| * If forceCreateTheSlot is true, then we must have created the "slot" for |
| * our TLS, even though we know that the return value will be nullptr in that |
| * case (i.e. no-slot and first-time-slot both return nullptr). This ensures |
| * that after calling GetSpecific, we know that we can legally call |
| * SetSpecific. |
| * |
| * If forceCreateTheSlot is false, then the impl can either create the |
| * slot or not. |
| */ |
| static void* PlatformGetSpecific(bool forceCreateTheSlot); |
| |
| /** |
| * Implemented by the platform, to set the value for our (one) slot per-thread |
| * |
| * The implementation can rely on GetSpecific(true) having been previously |
| * called before SetSpecific is called. |
| */ |
| static void PlatformSetSpecific(void*); |
| |
| public: |
| /** |
| * Will delete our internal list. To be called by the platform if/when its |
| * TLS slot is deleted (often at thread shutdown). |
| * |
| * Public *only* for the platform's use, not to be called by a client. |
| */ |
| static void Destructor(void* ptr); |
| }; |
| |
| #endif |