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Caching pattern: Documentation and diagram

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This commit is contained in:
Christoffer Hamberg
2016-10-09 12:43:43 +02:00
parent b31edda3cf
commit f114b5b957
7 changed files with 101 additions and 120 deletions
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1
caching/README.md
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@ -27,3 +27,4 @@ Use the Caching pattern(s) when
* [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained) * [Write-through, write-around, write-back: Cache explained](http://www.computerweekly.com/feature/Write-through-write-around-write-back-Cache-explained)
* [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177) * [Read-Through, Write-Through, Write-Behind, and Refresh-Ahead Caching](https://docs.oracle.com/cd/E15357_01/coh.360/e15723/cache_rtwtwbra.htm#COHDG5177)
* [Cache-Aside](https://msdn.microsoft.com/en-us/library/dn589799.aspx)

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190
caching/etc/caching.ucls
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@ -1,106 +1,90 @@
<?xml version="1.0" encoding="UTF-8"?> <?xml version="1.0" encoding="UTF-8"?>
<class-diagram version="1.1.8" icons="true" automaticImage="PNG" always-add-relationships="false" generalizations="true" <class-diagram version="1.1.11" icons="true" automaticImage="PNG" always-add-relationships="false"
realizations="true" associations="true" dependencies="false" nesting-relationships="true"> generalizations="true" realizations="true" associations="true" dependencies="false" nesting-relationships="true"
<class id="1" language="java" name="main.java.com.wssia.caching.App" project="CachingPatterns" router="FAN">
file="/CachingPatterns/src/main/java/com/wssia/caching/App.java" binary="false" corner="BOTTOM_RIGHT"> <class id="1" language="java" name="com.iluwatar.caching.CacheStore" project="caching"
<position height="-1" width="-1" x="249" y="150"/> file="/caching/src/main/java/com/iluwatar/caching/CacheStore.java" binary="false" corner="BOTTOM_RIGHT">
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" <position height="-1" width="-1" x="322" y="444"/>
sort-features="false" accessors="true" visibility="true"> <display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
<attributes public="true" package="true" protected="true" private="true" static="true"/> sort-features="false" accessors="true" visibility="true">
<operations public="true" package="true" protected="true" private="true" static="true"/> <attributes public="true" package="true" protected="true" private="true" static="true"/>
</display> <operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="2" language="java" name="com.iluwatar.caching.LruCache" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/LruCache.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="700" y="446"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<enumeration id="3" language="java" name="com.iluwatar.caching.CachingPolicy" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/CachingPolicy.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="943" y="122"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</enumeration>
<class id="4" language="java" name="com.iluwatar.caching.DbManager" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/DbManager.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="1011" y="426"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="5" language="java" name="com.iluwatar.caching.App" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/App.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="304" y="95"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="6" language="java" name="com.iluwatar.caching.AppManager" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/AppManager.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="604" y="122"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="7" language="java" name="com.iluwatar.caching.UserAccount" project="caching"
file="/caching/src/main/java/com/iluwatar/caching/UserAccount.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="1161" y="139"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class> </class>
<class id="2" language="java" name="main.java.com.wssia.caching.AppManager" project="CachingPatterns" <association id="8">
file="/CachingPatterns/src/main/java/com/wssia/caching/AppManager.java" binary="false" corner="BOTTOM_RIGHT"> <end type="SOURCE" refId="1" navigable="false">
<position height="-1" width="-1" x="502" y="163"/> <attribute id="9" name="cache"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" <multiplicity id="10" minimum="0" maximum="1"/>
sort-features="false" accessors="true" visibility="true"> </end>
<attributes public="true" package="true" protected="true" private="true" static="true"/> <end type="TARGET" refId="2" navigable="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/> <display labels="true" multiplicity="true"/>
</display> </association>
</class> <association id="11">
<class id="3" language="java" name="main.java.com.wssia.caching.CacheStore" project="CachingPatterns" <end type="SOURCE" refId="6" navigable="false">
file="/CachingPatterns/src/main/java/com/wssia/caching/CacheStore.java" binary="false" corner="BOTTOM_RIGHT"> <attribute id="12" name="cachingPolicy"/>
<position height="-1" width="-1" x="537" y="436"/> <multiplicity id="13" minimum="0" maximum="1"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true" </end>
sort-features="false" accessors="true" visibility="true"> <end type="TARGET" refId="3" navigable="true"/>
<attributes public="true" package="true" protected="true" private="true" static="true"/> <display labels="true" multiplicity="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/> </association>
</display> <classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
</class> sort-features="false" accessors="true" visibility="true">
<enumeration id="4" language="java" name="main.java.com.wssia.caching.CachingPolicy" project="CachingPatterns" <attributes public="true" package="true" protected="true" private="true" static="true"/>
file="/CachingPatterns/src/main/java/com/wssia/caching/CachingPolicy.java" binary="false" corner="BOTTOM_RIGHT"> <operations public="true" package="true" protected="true" private="true" static="true"/>
<position height="-1" width="-1" x="789" y="162"/> </classifier-display>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</enumeration>
<class id="5" language="java" name="main.java.com.wssia.caching.DBManager" project="CachingPatterns"
file="/CachingPatterns/src/main/java/com/wssia/caching/DBManager.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="1137" y="134"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="6" language="java" name="main.java.com.wssia.caching.LRUCache" project="CachingPatterns"
file="/CachingPatterns/src/main/java/com/wssia/caching/LRUCache.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="884" y="435"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="7" language="java" name="main.java.com.wssia.caching.UserAccount" project="CachingPatterns"
file="/CachingPatterns/src/main/java/com/wssia/caching/UserAccount.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="1140" y="405"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<class id="8" language="java" name="test.java.com.wssia.caching.AppTest" project="CachingPatterns"
file="/CachingPatterns/src/test/java/com/wssia/caching/AppTest.java" binary="false" corner="BOTTOM_RIGHT">
<position height="-1" width="-1" x="251" y="374"/>
<display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</display>
</class>
<association id="9">
<end type="SOURCE" refId="2" navigable="false">
<attribute id="10" name="cachingPolicy"/>
<multiplicity id="11" minimum="0" maximum="1"/>
</end>
<end type="TARGET" refId="4" navigable="true"/>
<display labels="true" multiplicity="true"/>
</association>
<association id="12">
<end type="SOURCE" refId="8" navigable="false">
<attribute id="13" name="app"/>
<multiplicity id="14" minimum="0" maximum="1"/>
</end>
<end type="TARGET" refId="1" navigable="true"/>
<display labels="true" multiplicity="true"/>
</association>
<association id="15">
<end type="SOURCE" refId="3" navigable="false">
<attribute id="16" name="cache"/>
<multiplicity id="17" minimum="0" maximum="1"/>
</end>
<end type="TARGET" refId="6" navigable="true"/>
<display labels="true" multiplicity="true"/>
</association>
<classifier-display autosize="true" stereotype="true" package="true" initial-value="false" signature="true"
sort-features="false" accessors="true" visibility="true">
<attributes public="true" package="true" protected="true" private="true" static="true"/>
<operations public="true" package="true" protected="true" private="true" static="true"/>
</classifier-display>
<association-display labels="true" multiplicity="true"/> <association-display labels="true" multiplicity="true"/>
</class-diagram> </class-diagram>

23
caching/src/main/java/com/iluwatar/caching/App.java
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@ -26,22 +26,23 @@ package com.iluwatar.caching;
* *
* The Caching pattern describes how to avoid expensive re-acquisition of resources by not releasing * The Caching pattern describes how to avoid expensive re-acquisition of resources by not releasing
* the resources immediately after their use. The resources retain their identity, are kept in some * the resources immediately after their use. The resources retain their identity, are kept in some
* fast-access storage, and are re-used to avoid having to acquire them again. There are three main * fast-access storage, and are re-used to avoid having to acquire them again. There are four main
* caching strategies/techniques in this pattern; each with their own pros and cons. They are: * caching strategies/techniques in this pattern; each with their own pros and cons. They are;
* <code>write-through</code> which writes data to the cache and DB in a single transaction, * <code>write-through</code> which writes data to the cache and DB in a single transaction,
* <code>write-around</code> which writes data immediately into the DB instead of the cache, and * <code>write-around</code> which writes data immediately into the DB instead of the cache,
* <code>write-behind</code> which writes data into the cache initially whilst the data is only * <code>write-behind</code> which writes data into the cache initially whilst the data is only
* written into the DB when the cache is full. The <code>read-through</code> strategy is also * written into the DB when the cache is full, and <code>cache-aside</code> which pushes the
* included in the mentioned three strategies -- returns data from the cache to the caller <b>if</b> * responsibility of keeping the data synchronized in both data sources to the application itself.
* it exists <b>else</b> queries from DB and stores it into the cache for future use. These * The <code>read-through</code> strategy is also included in the mentioned four strategies --
* strategies determine when the data in the cache should be written back to the backing store (i.e. * returns data from the cache to the caller <b>if</b> it exists <b>else</b> queries from DB and
* Database) and help keep both data sources synchronized/up-to-date. This pattern can improve * stores it into the cache for future use. These strategies determine when the data in the cache
* performance and also helps to maintain consistency between data held in the cache and the data in * should be written back to the backing store (i.e. Database) and help keep both data sources
* the underlying data store. * synchronized/up-to-date. This pattern can improve performance and also helps to maintain
* consistency between data held in the cache and the data in the underlying data store.
* <p> * <p>
* In this example, the user account ({@link UserAccount}) entity is used as the underlying * In this example, the user account ({@link UserAccount}) entity is used as the underlying
* application data. The cache itself is implemented as an internal (Java) data structure. It adopts * application data. The cache itself is implemented as an internal (Java) data structure. It adopts
* a Least-Recently-Used (LRU) strategy for evicting data from itself when its full. The three * a Least-Recently-Used (LRU) strategy for evicting data from itself when its full. The four
* strategies are individually tested. The testing of the cache is restricted towards saving and * strategies are individually tested. The testing of the cache is restricted towards saving and
* querying of user accounts from the underlying data store ( {@link DbManager}). The main class ( * querying of user accounts from the underlying data store ( {@link DbManager}). The main class (
* {@link App} is not aware of the underlying mechanics of the application (i.e. save and query) and * {@link App} is not aware of the underlying mechanics of the application (i.e. save and query) and

2
caching/src/main/java/com/iluwatar/caching/CachingPolicy.java
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@ -24,7 +24,7 @@ package com.iluwatar.caching;
/** /**
* *
* Enum class containing the three caching strategies implemented in the pattern. * Enum class containing the four caching strategies implemented in the pattern.
* *
*/ */
public enum CachingPolicy { public enum CachingPolicy {

3
caching/src/main/java/com/iluwatar/caching/LruCache.java
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@ -73,7 +73,6 @@ public class LruCache {
} }
/** /**
*
* Remove node from linked list. * Remove node from linked list.
*/ */
public void remove(Node node) { public void remove(Node node) {
@ -90,7 +89,6 @@ public class LruCache {
} }
/** /**
*
* Move node to the front of the list. * Move node to the front of the list.
*/ */
public void setHead(Node node) { public void setHead(Node node) {
@ -161,7 +159,6 @@ public class LruCache {
} }
/** /**
*
* Returns cache data in list form. * Returns cache data in list form.
*/ */
public List<UserAccount> getCacheDataInListForm() { public List<UserAccount> getCacheDataInListForm() {

2
caching/src/main/java/com/iluwatar/caching/UserAccount.java
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@ -23,9 +23,7 @@
package com.iluwatar.caching; package com.iluwatar.caching;
/** /**
*
* Entity class (stored in cache and DB) used in the application. * Entity class (stored in cache and DB) used in the application.
*
*/ */
public class UserAccount { public class UserAccount {
private String userId; private String userId;