GPU Program Caching

gpu/command_buffer/service/program_cache.h

+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef GPU_COMMAND_BUFFER_SERVICE_program_cache_H_
+#define GPU_COMMAND_BUFFER_SERVICE_program_cache_H_
+#pragma once
+
+#include <map>
+
+#include "base/hash_tables.h"
+#include "base/memory/weak_ptr.h"
+#include "base/sha1.h"
+#include "gpu/command_buffer/common/gles2_cmd_format.h"
+#include "gpu/command_buffer/service/shader_manager.h"
+
+namespace gpu {
+
+namespace gles2 {
+const uint32 kMaxProgramCacheSizeBytes = 20*1024*1024;
+
+struct CachedProgramKey {
+  CachedProgramKey()
+    : hashed_src_0(NULL),
+      hashed_src_1(NULL),
+      bind_attrib_location_map(NULL) { };
+  CachedProgramKey(
+      const unsigned char* _hashed_src_0,
+      const unsigned char* _hashed_src_1,
+      const std::map<std::string, GLint>* _bind_attrib_location_map)
+      : hashed_src_0(_hashed_src_0),
+        hashed_src_1(_hashed_src_1),
+        bind_attrib_location_map(_bind_attrib_location_map) {
+  }
+  ;
+  const unsigned char* hashed_src_0;

[greggman, 2012/06/19 22:27:50]

what's the point in these being char* instead of std::string?

Also what's the point of having this at all? If the keys are SHA1s then
CachedProgramKey should just be std::string.


You'd make the key by copying all the data to a buffer and running SHA1 at the
buffer at the time you need the key.

size_t buffer_size = ComputeSizeNeededForKeyData(src0, src1, location_map,
etc...);
scoped_array(new uint8[buffer_size]);

Then fill out the buffer

uint8* p = buffer.get();
memcpy(p, src0.c_str(), src0.size());
p += src0.size();
p++ = '\0';
memcpy(p, src1.c_str(), src1.size());
p += src1.size();
p++ = '\0';
etc.

then finally 

unsigned char key_buffer[kSHA1Length]
base::SHA1HashBytes(buffer_.get(), buffer_size, key_buffer);
std::string key(key_buffer, key_buffer + kSHA1Length);

[dmurph, 2012/06/23 01:37:28]

Done.

+  const unsigned char* hashed_src_1;
+  const std::map<std::string, GLint>* bind_attrib_location_map;
+};
+
+namespace {
+// sbdm hash function
+inline uint32 sbdm(const unsigned char *str) {
+  unsigned int hash = 0;
+  int c;
+  while ((c = *str++))
+    hash = c + (hash << 6) + (hash << 16) - hash;
+  return hash;
+}
+} // anonymous namespace
+
+struct CachedShaderKeyHash {
+  inline size_t operator()(const unsigned char* key) const {
+    return sbdm(key);
+  }
+};
+
+struct CachedShaderKeyEquals {
+  inline bool operator()(const unsigned char* a, const unsigned char* b) const {
+    return strcmp(reinterpret_cast<const char*>(a),
+                  reinterpret_cast<const char*>(b)) == 0;
+  }
+};
+
+struct CachedProgramKeyHash {
+  inline size_t operator()(const CachedProgramKey& key) const {
+    uint32 hash = sbdm(key.hashed_src_0);
+    hash = (hash << 6) + (hash << 16) - hash + sbdm(key.hashed_src_1);
+    if(key.bind_attrib_location_map) {
+      std::map<std::string, GLint>::const_iterator it;
+      for(it = key.bind_attrib_location_map->begin();
+          it != key.bind_attrib_location_map->end();
+          it++) {
+        const unsigned char* key =
+            reinterpret_cast<const unsigned char*>(it->first.c_str());
+        hash = (hash << 6) + (hash << 16) - hash + sbdm(key);
+        hash = (hash << 6) + (hash << 16) - hash + it->second;
+      }
+    }
+    return hash;
+  }
+};
+
+struct CachedProgramKeyEquals {
+  inline bool operator()(const CachedProgramKey& a,
+                         const CachedProgramKey& b) const {
+    return strcmp(reinterpret_cast<const char*>(a.hashed_src_0),
+                  reinterpret_cast<const char*>(b.hashed_src_0)) == 0 &&
+           strcmp(reinterpret_cast<const char*>(a.hashed_src_1),
+                  reinterpret_cast<const char*>(b.hashed_src_1)) == 0;
+  }
+};
+
+// Program cache base class for caching linked gpu programs
+class GPU_EXPORT ProgramCache : public base::SupportsWeakPtr<ProgramCache>{
+ public:
+  enum CompiledShaderStatus {
+    COMPILATION_UNKNOWN,
+    COMPILATION_SUCCEEDED
+  };
+
+  enum LinkedProgramStatus {
+    LINK_UNKNOWN,
+    LINK_SUCCEEDED
+  };
+
+  typedef base::hash_map<const unsigned char*,
+                         CompiledShaderStatus,
+                         CachedShaderKeyHash,
+                         CachedShaderKeyEquals> compile_status_map;
+  typedef base::hash_map<CachedProgramKey,
+                         LinkedProgramStatus,
+                         CachedProgramKeyHash,
+                         CachedProgramKeyEquals> link_status_map;
+
+  ProgramCache() : max_bytes_(kMaxProgramCacheSizeBytes) {}
+  virtual ~ProgramCache();
+
+  CompiledShaderStatus GetShaderCompilationStatus(
+      const std::string& shader_src) const;
+  void SetShaderCompilationStatus(const std::string& shader_src,
+                                  CompiledShaderStatus status);
+
+  LinkedProgramStatus GetLinkedProgramStatus(
+      const std::string& untranslated_a,
+      const std::string& untranslated_b,
+      std::map<std::string, GLint>* bind_attrib_location_map) const;
+  void SetLinkedProgramStatus(
+      const std::string& untranslated_a,
+      const std::string& untranslated_b,
+      std::map<std::string, GLint>* bind_attrib_location_map,
+      LinkedProgramStatus status);
+
+  virtual void LoadLinkedProgram(
+      GLuint program,
+      ShaderManager::ShaderInfo* shader_a,
+      ShaderManager::ShaderInfo* shader_b,
+      std::map<std::string, GLint>* bind_attrib_location_map) const = 0;
+  virtual void SaveLinkedProgram(
+      GLuint program,
+      ShaderManager::ShaderInfo* shader_a,
+      ShaderManager::ShaderInfo* shader_b,
+      std::map<std::string, GLint>* bind_attrib_location_map) = 0;
+
+  uint32 max_bytes() { return max_bytes_; }
+
+ protected:
+  static const uint32 kHashLength = base::kSHA1Length + 1;
+  void computeHash(const std::string& str, unsigned char* hashResult) const;
+
+ private:
+  const uint32 max_bytes_;
+
+  compile_status_map shader_status_;
+  link_status_map link_status_;
+
+  DISALLOW_COPY_AND_ASSIGN(ProgramCache);
+};
+} // namespace gles2
+} // namespace gpu
+
+#endif // GPU_COMMAND_BUFFER_SERVICE_program_cache_H_