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/*
* (c) Copyright 2018 Palantir Technologies Inc. All rights reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.palantir.lock;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonIgnore;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
import com.google.common.base.MoreObjects;
import com.google.common.collect.ImmutableSortedMap;
import com.palantir.logsafe.Preconditions;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.Serializable;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
/**
* Represents the result of calling {@link LockService#lockWithFullLockResponse(LockClient, LockRequest)} on
* the lock server. If locks were successfully acquired, then {@link #success()}
* returns true and {@link #getToken()} returns the token which
* represents the held locks.
*
* @author jtamer
*/
@JsonDeserialize(builder = LockResponse.SerializationProxy.class)
@Immutable
public final class LockResponse implements Serializable {
private static final long serialVersionUID = 0xd67972b13e30eff7L;
@Nullable
private final HeldLocksToken token;
private final boolean isBlockAndRelease;
private final ImmutableSortedMap lockHolders;
public LockResponse(@Nullable HeldLocksToken token) {
this(token, ImmutableSortedMap.of());
}
/**
* This should only get created by the Lock Service.
*/
public LockResponse(@Nullable HeldLocksToken token, Map lockHolders) {
this.token = token;
this.lockHolders = ImmutableSortedMap.copyOf(lockHolders);
isBlockAndRelease = false;
Preconditions.checkArgument(token != null || !this.lockHolders.isEmpty());
}
/**
* This should only get created by the Lock Service.
*
* This constructor is for {@link BlockingMode#BLOCK_INDEFINITELY_THEN_RELEASE}
*/
public LockResponse(Map lockHolders) {
this.token = null;
this.lockHolders = ImmutableSortedMap.copyOf(lockHolders);
assert this.lockHolders.isEmpty();
isBlockAndRelease = true;
}
/**
* Creates a new, successful {@code LockResponse} wrapping the given token,
* with an empty lock holders map.
*/
public static LockResponse createSuccessful(HeldLocksToken token) {
return new LockResponse(Preconditions.checkNotNull(token), ImmutableSortedMap.of());
}
/**
* Returns true if locks were acquired. Note that if the lock
* request specified {@link BlockingMode#BLOCK_INDEFINITELY} (the default
* behavior) or {@link BlockingMode#BLOCK_INDEFINITELY_THEN_RELEASE},
* then this method is guaranteed to return true.
*/
public boolean success() {
if (isBlockAndRelease) {
return lockHolders.isEmpty();
}
return token != null;
}
/**
* If {@link #success()} is true, then this method returns a token
* representing the held locks; otherwise, this method returns null.
*/
@Nullable
public HeldLocksToken getToken() {
return token;
}
@JsonIgnore
@Nullable
public LockRefreshToken getLockRefreshToken() {
return token == null ? null : token.getLockRefreshToken();
}
public boolean isBlockAndRelease() {
return isBlockAndRelease;
}
public List getLocks() {
return lockHolders.entrySet().stream()
.map(input -> ImmutableLockWithClient.builder()
.lockDescriptor(input.getKey())
.lockClient(input.getValue())
.build())
.collect(Collectors.toList());
}
/**
* Returns a map of lock descriptors and lock clients. Each entry's key is a
* lock which could not be acquired by the lock server, and its value is one
* of the clients who was already holding the lock. If multiple clients are
* holding a read lock, then one of those clients is picked arbitrarily to
* be used as the value in this map.
*
* Note that this map will not necessarily contain every lock which could
* not be acquired; however, if at least one of the requested locks was not
* acquired, then this map is guaranteed to contain at least one entry. Also
* note that even if {@link #success()} returns true, this map might
* not be empty if the lock request specified
* {@link LockGroupBehavior#LOCK_AS_MANY_AS_POSSIBLE}.
*/
@JsonIgnore
public ImmutableSortedMap getLockHolders() {
return lockHolders;
}
@Override
public boolean equals(@Nullable Object obj) {
if (this == obj) {
return true;
}
if (!(obj instanceof LockResponse)) {
return false;
}
return token.equals(((LockResponse) obj).token)
&& lockHolders.equals(((LockResponse) obj).getLockHolders())
&& isBlockAndRelease == ((LockResponse) obj).isBlockAndRelease();
}
@Override
public int hashCode() {
return Objects.hash(token, lockHolders, isBlockAndRelease);
}
public String toString(long currentTimeMillis) {
return MoreObjects.toStringHelper(getClass().getSimpleName())
.add("token", token.toString(currentTimeMillis))
.add("lockHolders", lockHolders)
.add("isBlockAndRelease", isBlockAndRelease)
.toString();
}
private void readObject(@SuppressWarnings("unused") ObjectInputStream in) throws InvalidObjectException {
throw new InvalidObjectException("proxy required");
}
private Object writeReplace() {
return new SerializationProxy(this);
}
static class SerializationProxy implements Serializable {
private static final long serialVersionUID = 0xcff22b33b08dd857L;
@Nullable
private final HeldLocksToken token;
private final ImmutableSortedMap lockHolders;
private final boolean isBlockAndRelease;
SerializationProxy(LockResponse lockResponse) {
this.token = lockResponse.token;
this.lockHolders = lockResponse.lockHolders;
this.isBlockAndRelease = lockResponse.isBlockAndRelease;
}
@JsonCreator
SerializationProxy(
@JsonProperty("token") HeldLocksToken token,
@JsonProperty("locks") List lockWithClients,
@JsonProperty("blockAndRelease") boolean isBlockAndRelease) {
if (lockWithClients == null) {
lockHolders = ImmutableSortedMap.of();
} else {
ImmutableSortedMap.Builder lockHoldersBuilder =
ImmutableSortedMap.naturalOrder();
for (LockWithClient lock : lockWithClients) {
lockHoldersBuilder.put(lock.getLockDescriptor(), lock.getLockClient());
}
this.lockHolders = lockHoldersBuilder.build();
}
this.token = token;
this.isBlockAndRelease = isBlockAndRelease;
}
public LockResponse build() {
return (LockResponse) readResolve();
}
Object readResolve() {
if (isBlockAndRelease) {
return new LockResponse(lockHolders);
}
return new LockResponse(token, lockHolders);
}
}
}