com.google.gerrit.server.query.change.ChangeNumberBitmapMaskAlgorithm Maven / Gradle / Ivy
// Copyright (C) 2022 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
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//
// 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,
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package com.google.gerrit.server.query.change;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.gerrit.server.config.GerritImportedServerIds;
import com.google.inject.Inject;
import com.google.inject.ProvisionException;
import com.google.inject.Singleton;
/**
* Dictionary-based encoding algorithm for combining a serverId/legacyChangeNum into a virtual
* numeric id
*
* TODO: To be reverted on master and stable-3.8
*/
@Singleton
public class ChangeNumberBitmapMaskAlgorithm implements ChangeNumberVirtualIdAlgorithm {
/*
* Bit-wise masks for representing the Change's VirtualId as combination of ServerId + ChangeNum:
*/
private static final int CHANGE_NUM_BIT_LEN = 28; // Allows up to 268M changes
private static final int LEGACY_ID_BIT_MASK = (1 << CHANGE_NUM_BIT_LEN) - 1;
private static final int SERVER_ID_BIT_LEN =
Integer.BYTES * 8 - CHANGE_NUM_BIT_LEN; // Allows up to 64 ServerIds
private final ImmutableMap serverIdCodes;
@Inject
public ChangeNumberBitmapMaskAlgorithm(
@GerritImportedServerIds ImmutableList importedServerIds) {
if (importedServerIds.size() >= 1 << SERVER_ID_BIT_LEN) {
throw new ProvisionException(
String.format(
"Too many imported GerritServerIds (%d) to fit into the Change virtual id",
importedServerIds.size()));
}
ImmutableMap.Builder serverIdCodesBuilder = new ImmutableMap.Builder<>();
for (int i = 0; i < importedServerIds.size(); i++) {
serverIdCodesBuilder.put(importedServerIds.get(i), i + 1);
}
serverIdCodes = serverIdCodesBuilder.build();
}
@Override
public int apply(String changeServerId, int changeNum) {
if ((changeNum & LEGACY_ID_BIT_MASK) != changeNum) {
throw new IllegalArgumentException(
String.format(
"Change number %d is too large to be converted into a virtual id", changeNum));
}
Integer encodedServerId = serverIdCodes.get(changeServerId);
if (encodedServerId == null) {
throw new IllegalArgumentException(
String.format("ServerId %s is not part of the GerritImportedServerIds", changeServerId));
}
int virtualId = (changeNum & LEGACY_ID_BIT_MASK) | (encodedServerId << CHANGE_NUM_BIT_LEN);
return virtualId;
}
}