ApplicationCache

== [[ApplicationCache]] ApplicationCache

ApplicationCache is...FIXME

ApplicationCache is <> exclusively when HistoryServer is HistoryServer.md#appCache[created].

ApplicationCache uses https://github.com/google/guava/wiki/Release14[Google Guava 14.0.1] library for the internal <>.

[[internal-registries]] .ApplicationCache's Internal Properties (e.g. Registries, Counters and Flags) [cols="1,2",options="header",width="100%"] |=== | Name | Description

| appLoader | [[appLoader]] Google Guava's https://google.github.io/guava/releases/14.0/api/docs/com/google/common/cache/CacheLoader.html[CacheLoader] with a custom ++https://google.github.io/guava/releases/14.0/api/docs/com/google/common/cache/CacheLoader.html#load(K)++[load] which is simply <>.

Used when...FIXME

| removalListener | [[removalListener]]

| appCache a| [[appCache]] Google Guava's https://google.github.io/guava/releases/14.0/api/docs/com/google/common/cache/LoadingCache.html[LoadingCache] of CacheKey keys and CacheEntry entries

Used when ApplicationCache is requested for the following:

• <> given appId and attemptId IDs

• FIXME (other uses)

| metrics | [[metrics]] |===

=== [[creating-instance]] Creating ApplicationCache Instance

ApplicationCache takes the following when created:

• [[operations]] ApplicationCacheOperations.md[ApplicationCacheOperations]
• [[retainedApplications]] retainedApplications
• [[clock]] Clock

ApplicationCache initializes the <>.

=== [[loadApplicationEntry]] loadApplicationEntry Internal Method

[source, scala]¶

loadApplicationEntry(appId: String, attemptId: Option[String]): CacheEntry¶

loadApplicationEntry...FIXME

NOTE: loadApplicationEntry is used exclusively when ApplicationCache is requested to <>.

=== [[load]] Loading Cached Spark Application UI -- load Method

[source, scala]¶

load(key: CacheKey): CacheEntry¶

NOTE: load is part of Google Guava's https://google.github.io/guava/releases/14.0/api/docs/com/google/common/cache/CacheLoader.html[CacheLoader] to retrieve a CacheEntry, based on a CacheKey, for <>.

load simply relays to <> with the appId and attemptId of the input CacheKey.

=== [[get]] Requesting Cached UI of Spark Application (CacheEntry) -- get Method

[source, scala]¶

get(appId: String, attemptId: Option[String] = None): CacheEntry¶

get...FIXME

NOTE: get is used exclusively when ApplicationCache is requested to <>.

=== [[withSparkUI]] Executing Closure While Holding Application's UI Read Lock -- withSparkUI Method

[source, scala]¶

withSparkUIT(fn: SparkUI => T): T¶

withSparkUI...FIXME

NOTE: withSparkUI is used when HistoryServer is requested to HistoryServer.md#withSparkUI[withSparkUI] and HistoryServer.md#loadAppUi[loadAppUi].