content/browser/code_cache/generated_code_cache_context.h

// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_CODE_CACHE_GENERATED_CODE_CACHE_CONTEXT_H_
#define CONTENT_BROWSER_CODE_CACHE_GENERATED_CODE_CACHE_CONTEXT_H_

#include <stdint.h>

#include <memory>
#include <optional>
#include <string>

#include "base/containers/span.h"
#include "base/files/file_path.h"
#include "base/functional/callback_forward.h"
#include "base/location.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_refptr.h"
#include "base/sequence_checker.h"
#include "base/task/sequenced_task_runner.h"
#include "base/thread_annotations.h"
#include "build/build_config.h"
#include "content/browser/code_cache/dedicated_task_runner_for_resource.h"
#include "content/common/content_export.h"
#include "content/public/browser/browser_thread.h"
#include "mojo/public/cpp/base/big_buffer.h"

#if !BUILDFLAG(IS_FUCHSIA)
#include "components/persistent_cache/entry_metadata.h"
#include "components/persistent_cache/pending_backend.h"
#include "components/persistent_cache/persistent_cache_collection.h"
#endif

namespace content {

class GeneratedCodeCache;

// One instance exists per disk-backed (non in-memory) storage contexts. This
// owns the instance of `GeneratedCodeCache` that is used to store the data
// generated by the renderer (for ex: code caches for script resources). This
// initializes and closes the code cache on the code cache thread. The
// instance of this class (`this`) itself is constructed on the UI thread.
class CONTENT_EXPORT GeneratedCodeCacheContext
    : public base::RefCountedThreadSafe<GeneratedCodeCacheContext> {
 public:
  REQUIRE_ADOPTION_FOR_REFCOUNTED_TYPE();

  // Runs a task on the code cache thread, or immediately if already on the code
  // cache thread.
  static void RunOrPostTask(scoped_refptr<GeneratedCodeCacheContext> context,
                            const base::Location& location,
                            base::OnceClosure task);

  // Gets the task runner for the code cache thread.
  static scoped_refptr<base::SequencedTaskRunner> GetTaskRunner(
      scoped_refptr<GeneratedCodeCacheContext> context);

  GeneratedCodeCacheContext();

  GeneratedCodeCacheContext(const GeneratedCodeCacheContext&) = delete;
  GeneratedCodeCacheContext& operator=(const GeneratedCodeCacheContext&) =
      delete;

  // Initialize is called on the UI thread when the StoragePartition is
  // being setup.
  void Initialize(const base::FilePath& path, int max_bytes);

  void Shutdown();

  // Shuts down the context and runs `callback` on the caller's sequence once
  // all background tasks have completed.
  void ShutdownForTesting(base::OnceClosure callback);

  // Call on the code cache thread to get the code cache instances.
  GeneratedCodeCache* generated_js_code_cache() const;
  GeneratedCodeCache* generated_wasm_code_cache() const;
  GeneratedCodeCache* generated_webui_js_code_cache() const;

  // Use to get rid of code cached in the PersistentCache collection both in
  // memory and persisted.
  void ClearAndDeletePersistentCacheCollection();

#if !BUILDFLAG(IS_FUCHSIA)
  // Returns a pending backend for an independent read-only connection to the
  // `context_key` cache, or nothing if it is not functional or the handles
  // cannot be exported. The returned value grants read access to all data
  // stored in the cache corresponding to `context_key`. Take care to only pass
  // it to the renderer for which it is intended; see
  // CodeCacheWithPersistentCacheHost::GetCacheId for more on this topic.
  std::optional<persistent_cache::PendingBackend> ShareReadOnlyConnection(
      const std::string& context_key);

  // Inserts `content` and `metadata` for `cache_key` in the cache identified by
  // `context_key`.
  void InsertIntoPersistentCacheCollection(
      const std::string& context_key,
      base::span<const uint8_t> cache_key,
      base::span<const uint8_t> content,
      persistent_cache::EntryMetadata metadata);

  // A simple container for the metadata associated with an entry in the cache
  // and the content that was cached. (The content is separate from the metadata
  // so that consumers of PersistentCache can control allocation of the memory
  // and the data type holding it.)
  struct MetadataAndContent {
    persistent_cache::EntryMetadata metadata;
    mojo_base::BigBuffer content;
  };

  // Returns the entry for `cache_key` in the cache identified by `context_key`,
  // or no value in case of a cache miss or retrieval error.
  std::optional<MetadataAndContent> FindInPersistentCacheCollection(
      const std::string& context_key,
      base::span<const uint8_t> cache_key);
#endif  // !BUILDFLAG(IS_FUCHSIA)

 private:
  friend class base::RefCountedThreadSafe<GeneratedCodeCacheContext>;
  ~GeneratedCodeCacheContext();

  void InitializeOnThread(const base::FilePath& path, int max_bytes);
  void ShutdownOnThread(
      DedicatedTaskRunnerForResource task_runner_for_resource);
  void ShutdownOnThreadForTesting(
      base::OnceClosure callback,
      DedicatedTaskRunnerForResource task_runner_for_resource);

  // Created, used and deleted on the code cache thread. Disabled when
  // PersistentCacheForCodeCache is enabled.
  std::unique_ptr<GeneratedCodeCache> generated_js_code_cache_
      GUARDED_BY_CONTEXT(sequence_checker_);
  std::unique_ptr<GeneratedCodeCache> generated_wasm_code_cache_
      GUARDED_BY_CONTEXT(sequence_checker_);
  std::unique_ptr<GeneratedCodeCache> generated_webui_js_code_cache_
      GUARDED_BY_CONTEXT(sequence_checker_);

#if !BUILDFLAG(IS_FUCHSIA)
  // Created and used when either PersistentCacheForCodeCache or
  // InlineScriptCache is enabled.
  // When the former is enabled, this replaces all of `generated_*_code_cache_`
  // above and stores the code following the same isolation principles but using
  // two keys instead of one. The first key is used to get a `PersistentCache`
  // associated with an isolation context from the collection. This ensures that
  // each isolation context uses a separate database file. The second key is the
  // prefixed resource URL of a serialized script.
  // When the latter is enabled, this stores source-keyed code cache entries
  // with the two-keys keying. The second key is the source hash digest (SHA256)
  // of a serialized script.
  // Note that those two features can be enabled at the same time and share the
  // same collection in that case.
  std::unique_ptr<persistent_cache::PersistentCacheCollection>
      persistent_cache_collection_ GUARDED_BY_CONTEXT(sequence_checker_);
#endif  // !BUILDFLAG(IS_FUCHSIA)

  // A handle that keeps a TaskRunner associated with this context's path alive
  // for as long as this instance operates on files within that path.
  DedicatedTaskRunnerForResource task_runner_for_resource_;
  scoped_refptr<base::SequencedTaskRunner> task_runner_;
  SEQUENCE_CHECKER(sequence_checker_);
};

}  // namespace content

#endif  // CONTENT_BROWSER_CODE_CACHE_GENERATED_CODE_CACHE_CONTEXT_H_