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Merge pull request #434 from tbak/refactorings/string_cache
1.x Cache string values to reduce memory footprint.
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65 changes: 65 additions & 0 deletions
65
eureka-client/src/main/java/com/netflix/discovery/converters/StringCache.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,65 @@ | ||
| package com.netflix.discovery.converters; | ||
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| import java.lang.ref.WeakReference; | ||
| import java.util.Map; | ||
| import java.util.WeakHashMap; | ||
| import java.util.concurrent.locks.ReadWriteLock; | ||
| import java.util.concurrent.locks.ReentrantReadWriteLock; | ||
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| /** | ||
| * @author Tomasz Bak | ||
| */ | ||
| public class StringCache { | ||
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| public static final int LENGTH_LIMIT = 38; | ||
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| private final ReadWriteLock lock = new ReentrantReadWriteLock(); | ||
| private final Map<String, WeakReference<String>> cache = new WeakHashMap<>(); | ||
| private final int lengthLimit; | ||
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| public StringCache() { | ||
| this(LENGTH_LIMIT); | ||
| } | ||
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| public StringCache(int lengthLimit) { | ||
| this.lengthLimit = lengthLimit; | ||
| } | ||
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| public String cachedValueOf(final String str) { | ||
| if (str != null && (lengthLimit < 0 || str.length() <= lengthLimit)) { | ||
| // Return value from cache if available | ||
| try { | ||
| lock.readLock().lock(); | ||
| WeakReference<String> ref = cache.get(str); | ||
| if (ref != null) { | ||
| return ref.get(); | ||
| } | ||
| } finally { | ||
| lock.readLock().unlock(); | ||
| } | ||
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| // Update cache with new content | ||
| try { | ||
| lock.writeLock().lock(); | ||
| WeakReference<String> ref = cache.get(str); | ||
| if (ref != null) { | ||
| return ref.get(); | ||
| } | ||
| cache.put(str, new WeakReference<String>(str)); | ||
| } finally { | ||
| lock.writeLock().unlock(); | ||
| } | ||
| return str; | ||
| } | ||
| return str; | ||
| } | ||
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| public int size() { | ||
| try { | ||
| lock.readLock().lock(); | ||
| return cache.size(); | ||
| } finally { | ||
| lock.readLock().unlock(); | ||
| } | ||
| } | ||
| } |
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35 changes: 35 additions & 0 deletions
35
eureka-client/src/test/java/com/netflix/discovery/converters/StringCacheTest.java
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,35 @@ | ||
| package com.netflix.discovery.converters; | ||
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| import org.junit.Test; | ||
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| import static org.junit.Assert.assertTrue; | ||
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| /** | ||
| * @author Tomasz Bak | ||
| */ | ||
| public class StringCacheTest { | ||
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| public static final int CACHE_SIZE = 100000; | ||
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| @Test | ||
| public void testVerifyStringsAreGarbageCollectedIfNotReferenced() throws Exception { | ||
| StringCache cache = new StringCache(); | ||
| for (int i = 0; i < CACHE_SIZE; i++) { | ||
| cache.cachedValueOf("id#" + i); | ||
| } | ||
| gc(); | ||
| // Testing GC behavior is unpredictable, so we set here low target level | ||
| // The tests run on desktop show that all strings are removed actually. | ||
| assertTrue(cache.size() < CACHE_SIZE * 0.1); | ||
| } | ||
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| public static void gc() { | ||
| System.gc(); | ||
| System.runFinalization(); | ||
| try { | ||
| Thread.sleep(1000); | ||
| } catch (InterruptedException e) { | ||
| // IGNORE | ||
| } | ||
| } | ||
| } |
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