History log of /frameworks/base/core/java/android/print/IPrintSpoolerCallbacks.aidl
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2fbd2a7f070f246ddafd9de94efa9a98861e9136 17-Sep-2013 Svetoslav <svetoslavganov@google.com> App UI freezes when printing. API clean up.

1. The UI of a printing app was freezing a little when calling the print
method since the print manager service was waiting for it to bind to the
print spooler which generated the print job id (and the initial print
job info really). Now the print manager service is responsible for job
id generation and does not not wait for the print spooler to spin. Hence,
the app UI is not blocked at all. Note that the print manager initiates
the binding to the spooler and as soon as it completes the spooler shows
the print UI which is hosted in its process. It is not possible to show
the print UI before the system is bound to the spooler since during this
binding the system passes a callback to the spooler so the latter can
talk to the system.

2. Changed the print job id to be an opaque class allowing us to vary the
way we generate print job ids in the future.

3. The queued print job state was hidden but the print job returned by the
print method of the print manager is in that state. Now now hidden.

4. We were incorrecly removing print job infos if they are completed or
cancelled. Doing that is problematic since the print job returned by
the print method allows the app to query for the job info after the
job has been say completed. Hence, an app can initiate printing and
get a print job whose state is "created" and hold onto it until after
the job is completed, now if the app asks for the print job info it
will get an info in "created" state even though the job is "completed"
since the spooler was not retaining the completed jobs. Now the spooler
removes the PDF files for the completed and cancelled print jobs but
keeps around the infos (also persisting them to disc) so it can answer
questions about them. On first boot or switch to a user we purge the
persisted print jobs in completed/cancelled state since they
are obsolete - no app can have a handle to them.

5. Removed the print method that takes a file since we have a public
PrintDocumentAdapter implementation for printing files. Once can
instantiate a PrintFileDocumentAdapter and pass it to the print
method. This class also allows overriding of the finish method to
know when the data is spooled and deleted the file if desired, etc.

6. Replaced the wrong code to slice a large list of parcelables to
use ParceledListSlice class.

bug:10748093

Change-Id: I1ebeeb47576e88fce550851cdd3e401fcede6e2b
/frameworks/base/core/java/android/print/IPrintSpoolerCallbacks.aidl
85b1f883056a1d74473fd9ce774948878f389ab6 25-Jul-2013 Svetoslav Ganov <svetoslavganov@google.com> Iteration on the print sub-system.

1. API changes: Moved copies API from PrintAttributes to PrintJobInfo;
Changed the PageRange list to an array in PrintDocumentAdapter#onWrite;
Added onCancelled method to the layout and write callbacks.

2. Refactored the serialization of remote layout and write commands. Now
the commands are serialized by the code in the client instead in the spooler.
The benefit is simple code since the client has to do a serialization to delegate
to the main thread anyway. The increased IPC found is fine since these calls
are quite unfrequent.

3. Removed an unused file: IPrintSpoolerObserver.aidl

4. Added equals and hasCode implementation to PageRange, PrintAttributes,
MediaSize, Resolution, Margins, Tray, PrintDocumentInfo.

5. Added shortcut path for query APIs on PrintJob that return cached values
if the print job is in a uncuttable state, i.e. completed or cancelled. Failed
print jobs can be restarted.

6. PrintJobInfo was not properly serialized.

7. Updated the look of the print dialog to be stable if there is and there isn't
currently selected printer.

8. PrintJobCOnfigActivity now calls onLayout on every print attributes change
but requests a write only on print preview or print button press. Also if the
layout did not change the content and it is already written no subsequent
call is made. Also if the selected pages change and we already have them
no subsequent call to write is made. Also the app is called with print preview
attribute set when performing layout and with it cleared after the print button
is pressed. A lot of changes making sure that only valid actions are enabled
in the activity (looks like a dialog) at a given time frame. The print job config
activity is also hidden after we got all the data, i.e. layout and write are done.

9. The callback from the print spooler to the system are scheduled via messages
to avoid lock being held during the call. It was hard to guarantee that since a
method holding a lock may be calling one that would like to release the lock
at some point to make the callbacks.

10. Print spooler state is persisted only if something changes in a completed
print job, i.e. not one that is being constructed due the print job config dialog.

11. Fixed a potential race in the RemotePrintSpooler where it was possible that
a client that got a handle to the remote spooler calls into an unbound spooler.
E.g: the client gets the remote interface with a lock held, now the client releases
the lock to avoid IPC with a lock, during the IPC scheduling the spooler has
notified the system that it is done and the system unbinds from it, now the
client's IPC is made to a spooler that is disconnected.

Change-Id: Ie9c42255940a27ecaed21a4d326a663a4788ac9d
/frameworks/base/core/java/android/print/IPrintSpoolerCallbacks.aidl
a00271533f639c8ed36429c663889ac9f654bc72 25-Jun-2013 Svetoslav Ganov <svetoslavganov@google.com> Refactoring of the print sub-system and API clean up.

1. Now a user state has ins own spooler since the spooler app is
running per user. The user state registers an observer for the state
of the spooler to get information needed to orchestrate unbinding
from print serivces that have no work and eventually unbinding from
the spooler when all no service has any work.

2. Abstracted a remote print service from the perspective of the system
in a class that is transparently managing binding and unbinding to
the remote instance.

3. Abstracted the remote print spooler to transparently manage binding
and unbinding to the remote instance when there is work and when
there is no work, respectively.

4. Cleaned up the print document adapter (ex-PrintAdapter) APIs to
enable implementing the all callbacks on a thread of choice. If
the document is really small, using the main thread makes sense.

Now if an app that does not need the UI state to layout the printed
content, it can schedule all the work for allocating resources, laying
out, writing, and releasing resources on a dedicated thread.

5. Added info class for the printed document that is now propagated
the the print services. A print service gets an instance of a
new document class that encapsulates the document info and a method
to access the document's data.

6. Added APIs for describing the type of a document to the new document
info class. This allows a print service to do smarts based on the
doc type. For now we have only photo and document types.

7. Renamed the systemReady method for system services that implement
it with different semantics to systemRunning. Such methods assume
the the service can run third-party code which is not the same as
systemReady.

8. Cleaned up the print job configuration activity.

9. Sigh... code clean up here and there. Factoring out classes to
improve readability.

Change-Id: I637ba28412793166cbf519273fdf022241159a92
/frameworks/base/core/java/android/print/IPrintSpoolerCallbacks.aidl