Differential updates for components.

chrome/browser/component_updater/component_updater_service.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 CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_
 #define CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_
 
 #include <string>
 #include <vector>
 
+#include "base/files/file_path.h"
 #include "base/version.h"
 #include "googleurl/src/gurl.h"
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace base {
 class DictionaryValue;
 class FilePath;

[cpu_(ooo_6.6-7.5), 2013/05/29 20:13:58]

note filepath is fwd declared here.

[waffles, 2013/06/13 20:55:04]

Done.

 }
 
+class ComponentPatcher;
+
 // Component specific installers must derive from this class and implement
 // OnUpdateError() and Install(). A valid instance of this class must be
 // given to ComponentUpdateService::RegisterComponent().
 class ComponentInstaller {
  public :
   // Called by the component updater on the UI thread when there was a
   // problem unpacking or verifying the component. |error| is a non-zero
   // value which is only meaningful to the component updater.
   virtual void OnUpdateError(int error) = 0;
 
   // Called by the component updater when a component has been unpacked
   // and is ready to be installed. |manifest| contains the CRX manifest
   // json dictionary and |unpack_path| contains the temporary directory
   // with all the unpacked CRX files.
   virtual bool Install(const base::DictionaryValue& manifest,
                        const base::FilePath& unpack_path) = 0;
 
+  // Set |installed_file| to the full path to the installed |file|. |file| is
+  // the filename of the file in this component's CRX. Returns false if this is
+  // not possible (the file has been removed or modified, or its current
+  // location is unknown). Otherwise, returns true.
+  virtual bool GetInstalledFile(const std::string& file,
+                                base::FilePath* installed_file) = 0;
+
  protected:
   virtual ~ComponentInstaller() {}
 };
 
 // Describes a particular component that can be installed or updated. This
 // structure is required to register a component with the component updater.
 // Only |name| is optional. |pk_hash| is the SHA256 hash of the component's
 // public key. If the component is to be installed then version should be
 // "0" or "0.0", else it should be the current version.
 // |source| is by default pointing to BANDAID but if needed it can be made
 // to point to the webstore (CWS_PUBLIC) or to the webstore sandbox. It is
 // important to note that the BANDAID source if active throught the day
 // can pre-empt updates from the other sources down the list.
 struct CrxComponent {
   // Specifies the source url for manifest check.
   enum UrlSource {
     BANDAID,
     CWS_PUBLIC,
-    CWS_SANDBOX
+    CWS_SANDBOX,
   };
 
   std::vector<uint8> pk_hash;
   ComponentInstaller* installer;
   Version version;
+  std::string fingerprint;

[cpu_(ooo_6.6-7.5), 2013/05/29 20:13:58]

if they have to provide the fingerprint, could this be something that the
ComponentInstaller can do? 

I imagine a scenario where we don't need the fingerprint until we have received
a reply from the server, or is that not how it works?

[waffles, 2013/06/13 20:55:04]

The fingerprint uniquely identifies the installed component (that is, it's a
stronger identifier than appid + version + operating system + etc); we must send
the current fingerprint to the server in the request so that the server knows
which package to give us the differential update from. The server then returns
the new fingerprint along with the response.

So, it feels like it belongs here with pk_hash and version, since it identifies
the currently installed package.

   std::string name;
   UrlSource source;
   CrxComponent();
   ~CrxComponent();
 };
 
 // The component update service is in charge of installing or upgrading
 // select parts of chrome. Each part is called a component and managed by
 // instances of CrxComponent registered using RegisterComponent(). On the
 // server, each component is packaged as a CRX which is the same format used
@@ skipping 35 matching lines @@
     virtual int NextCheckDelay() = 0;
     // Delay in seconds from each task step. Used to smooth out CPU/IO usage.
     virtual int StepDelay() = 0;
     // Minimum delta time in seconds before checking again the same component.
     virtual int MinimumReCheckWait() = 0;
     // Minimum delta time in seconds before an on-demand check is allowed
     // for the same component.
     virtual int OnDemandDelay() = 0;
     // The url that is going to be used update checks over Omaha protocol.
     virtual GURL UpdateUrl(CrxComponent::UrlSource source) = 0;
+    // The url where the completion pings are sent.
+    virtual GURL PingUrl() = 0;

[cpu_(ooo_6.6-7.5), 2013/05/29 20:13:58]

hmmm, I already receive complains about undue QPS from the CU, does this mean we
are going to double the traffic to our servers?

[waffles, 2013/06/13 20:55:04]

We've addressed this out of band. For the record, a summary is below.

There will be between 50% and 100% increase in average QPS from the component
updater.
There will be between 60% and 100% increase in peak QPS from the component
updater.
(Increases will be closer to the higher end of this range when multiple
components are releasing, and closer to/at the low end of this range on a daily
basis thanks to CRLSet's 12-hour update cycle.

The services that are going to receive this traffic have given the go-ahead.

     // Parameters added to each url request. It can be null if none are needed.
     virtual const char* ExtraRequestParams() = 0;
     // How big each update request can be. Don't go above 2000.
     virtual size_t UrlSizeLimit() = 0;
     // The source of contexts for all the url requests.
     virtual net::URLRequestContextGetter* RequestContext() = 0;
     // True means that all ops are performed in this process.
     virtual bool InProcess() = 0;
     // The component updater will call this function when an interesting event
     // happens. It should be used mostly as a place to add application specific
     // logging or telemetry. |extra| is |event| dependent.
     virtual void OnEvent(Events event, int extra) = 0;
+    // Creates a new ComponentPatcher in a platform-specific way. This is useful
+    // for dependency injection.
+    virtual ComponentPatcher* CreateComponentPatcher() = 0;
+    // True means that this client can handle delta updates.
+    virtual bool DeltasEnabled() const = 0;
+    // True means this client is allowed to send component update status pings.
+    virtual bool PingsEnabled() const = 0;
   };
 
   // Start doing update checks and installing new versions of registered
   // components after Configurator::InitialDelay() seconds.
   virtual Status Start() = 0;
 
   // Stop doing update checks. In-flight requests and pending installations
   // will not be canceled.
   virtual Status Stop() = 0;
 
@@ skipping 14 matching lines @@
 
   virtual ~ComponentUpdateService() {}
 };
 
 // Creates the component updater. You must pass a valid |config| allocated on
 // the heap which the component updater will own.
 ComponentUpdateService* ComponentUpdateServiceFactory(
     ComponentUpdateService::Configurator* config);
 
 #endif  // CHROME_BROWSER_COMPONENT_UPDATER_COMPONENT_UPDATER_SERVICE_H_