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1
5 package com.tc.object.cache;
6
7 import com.tc.logging.TCLogger;
8 import com.tc.logging.TCLogging;
9 import com.tc.runtime.MemoryEventType;
10 import com.tc.runtime.MemoryEventsListener;
11 import com.tc.runtime.MemoryUsage;
12 import com.tc.runtime.TCMemoryManagerImpl;
13 import com.tc.util.Assert;
14 import com.tc.util.State;
15
16 import java.util.List  ;
17
18 public class CacheManager implements MemoryEventsListener {
19
20 private static final TCLogger logger = TCLogging.getLogger(CacheManager.class);
21
22 private static final State INIT = new State("INIT");
23 private static final State PROCESSING = new State("PROCESSING");
24 private static final State COMPLETE = new State("COMPLETE");
25
26 private final Evictable evictable;
27 private final CacheConfig config;
28 private final TCMemoryManagerImpl memoryManager;
29
30 private int calculatedCacheSize = 0;
31 private CacheStatistics lastStat = null;
32
33 public CacheManager(Evictable evictable, CacheConfig config) {
34 this.evictable = evictable;
35 this.config = config;
36 this.memoryManager = new TCMemoryManagerImpl(config.getUsedThreshold(), config.getUsedCriticalThreshold(), config
37 .getSleepInterval(), config.getLeastCount(), config.isOnlyOldGenMonitored());
38 this.memoryManager.registerForMemoryEvents(this);
39 }
40
41 public void memoryUsed(MemoryEventType type, MemoryUsage usage) {
42 CacheStatistics cp = new CacheStatistics(type, usage);
43 evictable.evictCache(cp);
44 cp.validate();
45 addLastStat(cp);
46 }
47
48 private void addLastStat(CacheStatistics cp) {
50 this.lastStat = cp;
51 }
52
53 private final class CacheStatistics implements CacheStats {
54 private final MemoryEventType type;
55 private final MemoryUsage usage;
56
57 private int countBefore;
58 private int countAfter;
59 private int evicted;
60 private boolean objectsGCed = false;
61 private int toEvict;
62 private long startTime;
63 private State state = INIT;
64
65 public CacheStatistics(MemoryEventType type, MemoryUsage usage) {
66 this.type = type;
67 this.usage = usage;
68 }
69
70 public void validate() {
71 if (state == PROCESSING) {
72 throw new AssertionError (this + " : Object Evicted is not called. This indicates a bug in the software !");
74 }
75 }
76
77 public int getObjectCountToEvict(int currentCount) {
78 startTime = System.currentTimeMillis();
79 countBefore = currentCount;
80 adjustCachedObjectCount(currentCount);
81 toEvict = computeObjects2Evict(currentCount);
82 if (toEvict < 0 || toEvict > currentCount) {
83 throw new AssertionError ("Computed Object to evict is out of range : toEvict = " + toEvict + " currentCount = "
85 + currentCount + " " + this);
86 }
87 if (toEvict > 0) {
88 state = PROCESSING;
89 }
90 if (config.isLoggingEnabled()) {
91 logger.info("Asking to evict " + toEvict + " current size = " + currentCount + " calculated cache size = "
92 + calculatedCacheSize + " heap used = " + usage.getUsedPercentage() + " % gc count = "
93 + usage.getCollectionCount());
94 }
95 return this.toEvict;
96 }
97
98 private void adjustCachedObjectCount(int currentCount) {
106 if (type == MemoryEventType.BELOW_THRESHOLD || lastStat == null
107 || lastStat.usage.getCollectionCount() < usage.getCollectionCount()
108 || (usage.getCollectionCount() < 0 && lastStat.usage.getUsedMemory() > usage.getUsedMemory())) {
109 double used = usage.getUsedPercentage();
110 double threshold = config.getUsedThreshold();
111 Assert.assertTrue((type == MemoryEventType.BELOW_THRESHOLD && threshold >= used) || threshold <= used);
112 if (used > 0) calculatedCacheSize = (int) (currentCount * (threshold / used));
113 }
114 }
115
116 public void objectEvicted(int evictedCount, int currentCount, List targetObjects4GC) {
117 this.evicted = evictedCount;
118 this.countAfter = currentCount;
119 state = COMPLETE;
120 if (config.isLoggingEnabled()) {
122 logger.info("Evicted " + evictedCount + " current Size = " + currentCount + " new objects created = "
123 + getNewObjectsCount() + " time taken = " + (System.currentTimeMillis() - startTime) + " ms");
124 }
125 }
126
127 private int getNewObjectsCount() {
128 return countAfter - (countBefore - evicted);
129 }
130
131 private int computeObjects2Evict(int currentCount) {
134 if (type == MemoryEventType.BELOW_THRESHOLD || calculatedCacheSize > currentCount) { return 0; }
135 int overshoot = currentCount - calculatedCacheSize;
136 if (overshoot <= 0) return 0;
137 int objects2Evict = overshoot + ((calculatedCacheSize * config.getPercentageToEvict()) / 100);
138 return objects2Evict;
139 }
140
141 public String toString() {
142 return "CacheStats[ type = " + type + ",\n\t usage = " + usage + ",\n\t countBefore = " + countBefore
143 + ", toEvict = " + toEvict + ", evicted = " + evicted + ", countAfter = " + countAfter
144 + ", objectsGCed = " + objectsGCed + ",\n\t state = " + state + "]";
145 }
146 }
147
148 }
149 |
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