author Jim Blandy <>
Tue, 12 Feb 2019 08:16:16 +0000
changeset 458932 414b2c238839c321dee78a9d927c968f1e52ae79
parent 448947 6f3709b3878117466168c40affa7bca0b60cf75b
child 472056 e1993a1f09ac53cd1a04fdf6a87f8cad8e44f73e
permissions -rw-r--r--
Bug 1145201: Replace EnqueuePromiseJobCallback and GetIncumbentGlobalCallback with new JobQueue abstract base class. r=arai,smaug While the behavior of ECMAScript Promises and their associated job queue is covered by the ECMAScript standard, the HTML specification amends that with additional behavior the web platform requires. To support this, SpiderMonkey provides hooks the embedding can set to replace SpiderMonkey's queue with its own implementation. At present, these hooks are C-style function-pointer-and-void-pointer pairs, which are awkward to handle and mistake-prone, as passing a function the wrong void* is not a type error. Later patches in this series must add new hooks, making a bad situation worse. A C++ abstract base class is a well-typed alternative. This introduces a new `JS::JobQueue` abstract class, and adapts SpiderMonkey's internal job queue and Gecko's customization to use it. `GetIncumbentGlobalCallback` and `EnqueuePromiseJobCallback` become virtual methods. Within SpiderMonkey, the patch gathers the various fields of JSContext that implement the internal queue into their own type, js::InternalJobQueue. Various jsfriendapi functions become veneers for calls to methods specific to the derived class. The InternalJobQueue type itself remains private to SpiderMonkey, as it uses types like TraceableFifo, derived from Fifo, that are not part of SpiderMonkey's public API. Within Gecko, CycleCollectedJSContext acquires JS::JobQueue as a private base class, and a few static methods are cleaned up nicely. There are a few other hooks defined in js/public/Promise.h that might make sense to turn into virtual methods on JobQueue. For example, DispatchToEventLoopCallback, used for resolving promises of results from off-main-thread tasks, is probably necessarily connected to the JobQueue implementation in use, so it might not be sensible to set one without the other. But it was left unchanged to reduce this patch's size. Differential Revision:

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=2 et lcs=trail\:.,tab\:>~ :
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at */


#include "nsCOMPtr.h"
#include "nsICollation.h"
#include "nsIFile.h"
#include "nsIMemoryReporter.h"
#include "nsIObserver.h"
#include "nsTArray.h"
#include "mozilla/Mutex.h"

#include "mozIStorageService.h"

class nsIMemoryReporter;
struct sqlite3_vfs;

namespace mozilla {
namespace storage {

class Connection;
class Service : public mozIStorageService,
                public nsIObserver,
                public nsIMemoryReporter {
   * Initializes the service.  This must be called before any other function!
  nsresult initialize();

   * Compares two strings using the Service's locale-aware collation.
   * @param  aStr1
   *         The string to be compared against aStr2.
   * @param  aStr2
   *         The string to be compared against aStr1.
   * @param  aComparisonStrength
   *         The sorting strength, one of the nsICollation constants.
   * @return aStr1 - aStr2.  That is, if aStr1 < aStr2, returns a negative
   *         number.  If aStr1 > aStr2, returns a positive number.  If
   *         aStr1 == aStr2, returns 0.
  int localeCompareStrings(const nsAString &aStr1, const nsAString &aStr2,
                           int32_t aComparisonStrength);

  static already_AddRefed<Service> getSingleton();


   * Obtains the cached data for the preference.
  static int32_t getSynchronousPref();

   * Obtains the default page size for this platform. The default value is
   * specified in the SQLite makefile (SQLITE_DEFAULT_PAGE_SIZE) but it may be
   * overriden with the PREF_TS_PAGESIZE hidden preference.
  static int32_t getDefaultPageSize() { return sDefaultPageSize; }

   * Returns a boolean value indicating whether or not the given page size is
   * valid (currently understood as a power of 2 between 512 and 65536).
  static bool pageSizeIsValid(int32_t aPageSize) {
    return aPageSize == 512 || aPageSize == 1024 || aPageSize == 2048 ||
           aPageSize == 4096 || aPageSize == 8192 || aPageSize == 16384 ||
           aPageSize == 32768 || aPageSize == 65536;

   * Registers the connection with the storage service.  Connections are
   * registered so they can be iterated over.
   * @pre mRegistrationMutex is not held
   * @param  aConnection
   *         The connection to register.
  void registerConnection(Connection *aConnection);

   * Unregisters the connection with the storage service.
   * @pre mRegistrationMutex is not held
   * @param  aConnection
   *         The connection to unregister.
  void unregisterConnection(Connection *aConnection);

   * Gets the list of open connections.  Note that you must test each
   * connection with mozIStorageConnection::connectionReady before doing
   * anything with it, and skip it if it's not ready.
   * @pre mRegistrationMutex is not held
   * @param  aConnections
   *         An inout param;  it is cleared and the connections are appended to
   *         it.
   * @return The open connections.
  void getConnections(nsTArray<RefPtr<Connection> > &aConnections);

  virtual ~Service();

   * Used for 1) locking around calls when initializing connections so that we
   * can ensure that the state of sqlite3_enable_shared_cache is sane and 2)
   * synchronizing access to mLocaleCollation.
  Mutex mMutex;

  sqlite3_vfs *mSqliteVFS;

   * Protects mConnections.
  Mutex mRegistrationMutex;

   * The list of connections we have created.  Modifications to it are
   * protected by |mRegistrationMutex|.
  nsTArray<RefPtr<Connection> > mConnections;

   * Frees as much heap memory as possible from all of the known open
   * connections.
  void minimizeMemory();

   * Lazily creates and returns a collation created from the application's
   * locale that all statements of all Connections of this Service may use.
   * Since the collation's lifetime is that of the Service and no statement may
   * execute outside the lifetime of the Service, this method returns a raw
   * pointer.
  nsICollation *getLocaleCollation();

   * Lazily created collation that all statements of all Connections of this
   * Service may use.  The collation is created from the application's locale.
   * @note Collation implementations are platform-dependent and in general not
   *       thread-safe.  Access to this collation should be synchronized.
  nsCOMPtr<nsICollation> mLocaleCollation;

  nsCOMPtr<nsIFile> mProfileStorageFile;

  nsCOMPtr<nsIMemoryReporter> mStorageSQLiteReporter;

  static Service *gService;

  static int32_t sSynchronousPref;
  static int32_t sDefaultPageSize;

}  // namespace storage
}  // namespace mozilla