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added try catch in computeifpresent to preserve old value incase of e… #5896

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added try catch in computeifpresent to preserve old value incase of e… #5896

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10 changes: 10 additions & 0 deletions guava-tests/test/com/google/common/cache/LocalCacheMapComputeTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -85,6 +85,16 @@ public void testComputeEviction() {
assertThat(c.asMap().computeIfAbsent("hash-2", k -> "")).isEqualTo("");
}

public void testComputeIfPresent_error() {
Cache<String, String> cache = CacheBuilder.newBuilder().build();
cache.put(key, "1");
try {
cache.asMap().computeIfPresent(key, (key, value) -> { throw new Error(); });
} catch (Error e) {}
assertEquals("1", cache.getIfPresent(key));
assertEquals("2", cache.asMap().computeIfPresent(key, (k, v) -> "2"));
}

public void testComputeIfPresent() {
cache.put(key, "1");
// simultaneous update for same key, expect count successful updates
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16 changes: 12 additions & 4 deletions guava/src/com/google/common/cache/LocalCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -4223,7 +4223,17 @@ public V computeIfAbsent(K key, Function<? super K, ? extends V> function) {
public V computeIfPresent(K key, BiFunction<? super K, ? super V, ? extends V> function) {
checkNotNull(key);
checkNotNull(function);
return compute(key, (k, oldValue) -> (oldValue == null) ? null : function.apply(k, oldValue));
return compute(key, (k, oldValue) -> {
try{
if(oldValue==null){
return null;
}
return function.apply(k, oldValue);
}catch (Throwable e){
this.put(k,oldValue);
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This is a bit sketchy, e.g. ConcurrentHashMap does not allow writes within a computation. I think it would be better to handle this within the compute method, even if a more complex method to understand.

throw e;
}
});
}

@Override
Expand Down Expand Up @@ -4907,9 +4917,7 @@ public long size() {
}

@Override
public ConcurrentMap<K, V> asMap() {
return localCache;
}
public ConcurrentMap<K, V> asMap() { return localCache; }

@Override
public CacheStats stats() {
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