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a14a5212ac
Summary:
Until now, we've been hiding transactions beneath the surface. When you call persistModel, you're implicitly creating a transaction.
You could explicitly create them with `atomically`..., but there were several critical problems that are fixed in this diff:
- Calling persistModel / unpersistModel within a transaction could cause the DatabaseStore to trigger. This could result in other parts of the app making queries /during/
the transaction, potentially before the COMMIT occurred and saved the changes. The new, explicit inTransaction syntax holds all changes until after COMMIT and then triggers.
- Calling atomically and then calling persistModel inside that resulted in us having to check whether a transaction was present and was gross.
- Many parts of the code ran extensive logic inside a promise chained within `atomically`:
BAD:
```
DatabaseStore.atomically =>
DatabaseStore.persistModel(draft) =>
GoMakeANetworkRequestThatReturnsAPromise
```
OVERWHELMINGLY BETTER:
```
DatabaseStore.inTransaction (t) =>
t.persistModel(draft)
.then =>
GoMakeANetworkRequestThatReturnsAPromise
```
Having explicit transactions also puts us on equal footing with Sequelize and other ORMs. Note that you /have/ to call DatabaseStore.inTransaction (t) =>. There is no other way to access the methods that let you alter the database. :-)
Other changes:
- This diff removes Message.labels and the Message-Labels table. We weren't using Message-level labels anywhere, and the table could grow very large.
- This diff changes the page size during initial sync from 250 => 200 in an effort to make transactions a bit faster.
Test Plan: Run tests!
Reviewers: juan, evan
Reviewed By: juan, evan
Differential Revision: https://phab.nylas.com/D2353
54 lines
1.4 KiB
CoffeeScript
54 lines
1.4 KiB
CoffeeScript
_ = require 'underscore'
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{NylasStore, DatabaseStore} = require 'nylas-exports'
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class RefreshingJSONCache
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constructor: ({@key, @version, @refreshInterval}) ->
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@_timeoutId = null
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start: ->
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# Clear any scheduled actions
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@end()
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# Look up existing data from db
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DatabaseStore.findJSONBlob(@key).then (json) =>
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# Refresh immediately if json is missing or version is outdated. Otherwise,
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# compute next refresh time and schedule
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timeUntilRefresh = 0
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if json? and json.version is @version
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timeUntilRefresh = Math.max(0, @refreshInterval - (Date.now() - json.time))
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@_timeoutId = setTimeout(@refresh, timeUntilRefresh)
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reset: ->
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# Clear db value, turn off any scheduled actions
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DatabaseStore.inTransaction (t) => t.persistJSONBlob(@key, {})
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@end()
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end: ->
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# Turn off any scheduled actions
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clearInterval(@_timeoutId) if @_timeoutId
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@_timeoutId = null
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refresh: =>
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# Set up next refresh call
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clearTimeout(@_timeoutId) if @_timeoutId
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@_timeoutId = setTimeout(@refresh, @refreshInterval)
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# Call fetch data function, save it to the database
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@fetchData (newValue) =>
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DatabaseStore.inTransaction (t) =>
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t.persistJSONBlob(@key, {
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version: @version
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time: Date.now()
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value: newValue
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})
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fetchData: (callback) =>
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throw new Error("Subclasses should override this method.")
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module.exports = RefreshingJSONCache
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