Bug 1705676 - Add CachePurgeLock to lock access to the purged cache directory r=nalexander,necko-reviewers,dragana

Depends on D132595

Differential Revision: https://phabricator.services.mozilla.com/D132164

netwerk/build/components.conf

@@ -675,3 +675,13 @@ if link_service:
             'singleton': True,
         }, **link_service)
     ]
+
+if toolkit != 'android':
+    Classes += [
+        {
+        'cid': '{72da39cc-0b9b-4fff-8ff9-d3b9a41d0dc4}',
+        'contract_ids': ['@mozilla.org/net/CachePurgeLock;1'],
+        'type': 'mozilla::net::CachePurgeLock',
+        'headers': ['mozilla/net/CachePurgeLock.h'],
+        },
+    ]

netwerk/cache2/CachePurgeLock.cpp

@@ -0,0 +1,76 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#include "CachePurgeLock.h"
+#include "nsCOMPtr.h"
+#include "nsIFile.h"
+#include "nsAppRunner.h"
+#include "mozilla/MultiInstanceLock.h"
+
+namespace mozilla::net {
+
+NS_IMPL_ISUPPORTS(CachePurgeLock, nsICachePurgeLock)
+
+NS_IMETHODIMP
+CachePurgeLock::Lock(const nsACString& profileName) {
+  nsresult rv;
+  if (mLock != MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    // Lock is already open.
+    return NS_OK;
+  }
+
+  nsCOMPtr<nsIFile> appFile = mozilla::GetNormalizedAppFile(nullptr);
+  if (!appFile) {
+    return NS_ERROR_NOT_AVAILABLE;
+  }
+
+  nsCOMPtr<nsIFile> appDirFile;
+  rv = appFile->GetParent(getter_AddRefs(appDirFile));
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoString appDirPath;
+  rv = appDirFile->GetPath(appDirPath);
+  NS_ENSURE_SUCCESS(rv, rv);
+
+  nsAutoCString lockName(profileName);
+  lockName.Append("-cachePurge");
+
+  mLock = mozilla::OpenMultiInstanceLock(lockName.get(), appDirPath.get());
+  if (mLock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    return NS_ERROR_FAILURE;
+  }
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+CachePurgeLock::IsOtherInstanceRunning(bool* aResult) {
+  if (NS_WARN_IF(XRE_GetProcessType() != GeckoProcessType_Default)) {
+    return NS_ERROR_SERVICE_NOT_AVAILABLE;
+  }
+
+  if (mLock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    return NS_ERROR_NOT_INITIALIZED;
+  }
+
+  bool rv = mozilla::IsOtherInstanceRunning(mLock, aResult);
+  NS_ENSURE_TRUE(rv, NS_ERROR_FAILURE);
+
+  return NS_OK;
+}
+
+NS_IMETHODIMP
+CachePurgeLock::Unlock() {
+  if (mLock == MULTI_INSTANCE_LOCK_HANDLE_ERROR) {
+    // Lock is already released.
+    return NS_OK;
+  }
+
+  mozilla::ReleaseMultiInstanceLock(mLock);
+  mLock = MULTI_INSTANCE_LOCK_HANDLE_ERROR;
+
+  return NS_OK;
+}
+
+}  // namespace mozilla::net

netwerk/cache2/CachePurgeLock.h

@@ -0,0 +1,24 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_net_CachePurgeLock_h__
+#define mozilla_net_CachePurgeLock_h__
+
+#include "nsICachePurgeLock.h"
+#include "mozilla/MultiInstanceLock.h"
+
+namespace mozilla::net {
+
+class CachePurgeLock : public nsICachePurgeLock {
+  NS_DECL_ISUPPORTS
+  NS_DECL_NSICACHEPURGELOCK
+ private:
+  virtual ~CachePurgeLock() = default;
+
+  MultiInstLockHandle mLock = MULTI_INSTANCE_LOCK_HANDLE_ERROR;
+};
+
+}  // namespace mozilla::net
+
+#endif  // mozilla_net_CachePurgeLock_h__

netwerk/cache2/moz.build

@@ -11,6 +11,7 @@ XPIDL_SOURCES += [
     "nsICacheEntry.idl",
     "nsICacheEntryDoomCallback.idl",
     "nsICacheEntryOpenCallback.idl",
+    "nsICachePurgeLock.idl",
     "nsICacheStorage.idl",
     "nsICacheStorageService.idl",
     "nsICacheStorageVisitor.idl",
@@ -24,6 +25,8 @@ EXPORTS += [
     "CacheStorageService.h",
 ]
 
+EXPORTS.mozilla.net += ["CachePurgeLock.h"]
+
 SOURCES += [
     "CacheStorage.cpp",
 ]
@@ -49,6 +52,11 @@ UNIFIED_SOURCES += [
     "CacheStorageService.cpp",
 ]
 
+if CONFIG["MOZ_WIDGET_TOOLKIT"] != "android":
+    UNIFIED_SOURCES += [
+        "CachePurgeLock.cpp",
+    ]
+
 LOCAL_INCLUDES += [
     "/netwerk/base",
     "/netwerk/cache",

netwerk/cache2/nsICachePurgeLock.idl

@@ -0,0 +1,33 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+#include "nsISupports.idl"
+
+/**
+ * This object is a wrapper of MultiInstanceLock.
+ * It's intended to be used to ensure exclusive access to folders being
+ * deleted by the purgeHTTPCache background task.
+ */
+[scriptable,uuid(8abb21e3-c6a0-4b4d-9333-cc0d72f2c23b)]
+interface nsICachePurgeLock : nsISupports {
+    /**
+     * Initializes the lock using the profile name and the current process's
+     * path.
+     * Will throw if a lock was already acquired successfully.
+     */
+    void lock(in AUTF8String profileName);
+
+    /**
+     * Returns true if another instance also holds the lock.
+     * Throws if called before lock was called, or after unlock was called.
+     */
+    bool isOtherInstanceRunning();
+
+    /**
+     * Releases the lock.
+     * This object may be locked again, potentially using a different path
+     * after unlocking.
+     */
+    void unlock();
+};