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FirefoxOS/Device Storage/Worker Design: Difference between revisions
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FirefoxOS/Device Storage/Worker Design (view source)
Revision as of 00:19, 10 June 2015
, 10 June 2015add notes on mime service
(→Expose Device Storage to workers: add implementation note about ensuring appropriate thread contexts and window references) |
(add notes on mime service) |
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This is only accessed on parent process, so there is no child process concerns. However since workers can also exist on the parent, it needs to be made thread safe. It may continue to be initialized on demand since it has no dependencies on the main thread. All operations besides initialization appear to run on a dedicated IO thread. As such, only the ::CreateOrGet method needs to be protected via a mutex. | This is only accessed on parent process, so there is no child process concerns. However since workers can also exist on the parent, it needs to be made thread safe. It may continue to be initialized on demand since it has no dependencies on the main thread. All operations besides initialization appear to run on a dedicated IO thread. As such, only the ::CreateOrGet method needs to be protected via a mutex. | ||
== MIME service == | |||
The MIME type of a file is queried for each file when an enumeration operation is requested. The MIME service can only be accessed on the main thread; this is problematic given that this would presently require a context switch to and from each time the user calls continue on our enumeration cursor. nsExternalHelperAppService::GetTypeFromFile extracts the file extension and check then checks that against the numerous sources of MIME information (consistent with the IDL description). We should switch to extracting the file extension ourselves, use nsExternalHelperAppService:::GetTypeFromExtension to get the MIME type on the main thread for unknown extensions as is done today, and cache the result for the duration of the enumeration cursor. This balances worker performance (i.e. very like that the number of files greatly exceeds the number of unique extensions) with accuracy (i.e. by caching only for a particular cursor request, we allow the underlying service to discover new MIME types by addition of plugins, etc if the enumeration is reattempted). | |||
== Device storage IPC API with child-parent processes == | == Device storage IPC API with child-parent processes == | ||