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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/base/status_with.h"
#include "mongo/db/jsobj.h"
namespace mongo {
/**
* ChunkVersions consist of a major/minor version scoped to a version epoch
*
* Version configurations (format: major version, epoch):
*
* 1. (0, 0) - collection is dropped.
* 2. (0, n), n > 0 - applicable only to shardVersion; shard has no chunk.
* 3. (n, 0), n > 0 - invalid configuration.
* 4. (n, m), n > 0, m > 0 - normal sharded collection version.
*
* TODO: This is a "manual type" but, even so, still needs to comform to what's
* expected from types.
*/
struct ChunkVersion {
public:
/**
* The name for the shard version information field, which shard-aware commands should include
* if they want to convey shard version.
*/
static constexpr StringData kShardVersionField = "shardVersion"_sd;
ChunkVersion() : _combined(0), _epoch(OID()) {}
ChunkVersion(uint32_t major, uint32_t minor, const OID& epoch)
: _combined(static_cast<uint64_t>(minor) | (static_cast<uint64_t>(major) << 32)),
_epoch(epoch) {}
static StatusWith<ChunkVersion> parseFromCommand(const BSONObj& obj) {
return parseWithField(obj, kShardVersionField);
}
/**
* Parses the BSON formatted by appendWithField. If the field is missing, returns 'NoSuchKey',
* otherwise if the field is not properly formatted can return any relevant parsing error
* (BadValue, TypeMismatch, etc).
*/
static StatusWith<ChunkVersion> parseWithField(const BSONObj& obj, StringData field);
/**
* NOTE: This format is being phased out. Use parseWithField instead.
*
* Parses the BSON formatted by appendLegacyWithField. If the field is missing, returns
* 'NoSuchKey', otherwise if the field is not properly formatted can return any relevant parsing
* error (BadValue, TypeMismatch, etc).
*/
static StatusWith<ChunkVersion> parseLegacyWithField(const BSONObj& obj, StringData field);
/**
* Indicates a dropped collection. All components are zeroes (OID is zero time, zero
* machineId/inc).
*/
static ChunkVersion DROPPED() {
return ChunkVersion(0, 0, OID());
}
/**
* Indicates that the collection is not sharded. Same as DROPPED.
*/
static ChunkVersion UNSHARDED() {
return ChunkVersion(0, 0, OID());
}
/**
* Indicates that the shard version checking must be skipped.
*/
static ChunkVersion IGNORED() {
ChunkVersion version = ChunkVersion();
version._epoch.init(Date_t(), true); // ignored OID is zero time, max machineId/inc
return version;
}
static bool isIgnoredVersion(const ChunkVersion& version) {
return version.majorVersion() == 0 && version.minorVersion() == 0 &&
version.epoch() == IGNORED().epoch();
}
void incMajor() {
_combined = static_cast<uint64_t>(majorVersion() + 1) << 32;
}
void incMinor() {
_combined++;
}
// Note: this shouldn't be used as a substitute for version except in specific cases -
// epochs make versions more complex
unsigned long long toLong() const {
return _combined;
}
bool isSet() const {
return _combined > 0;
}
uint32_t majorVersion() const {
return _combined >> 32;
}
uint32_t minorVersion() const {
return _combined & 0xFFFFFFFF;
}
const OID& epoch() const {
return _epoch;
}
//
// Explicit comparison operators - versions with epochs have non-trivial comparisons.
// > < operators do not check epoch cases. Generally if using == we need to handle
// more complex cases.
//
bool operator==(const ChunkVersion& otherVersion) const {
return otherVersion.epoch() == epoch() && otherVersion._combined == _combined;
}
bool operator!=(const ChunkVersion& otherVersion) const {
return !(otherVersion == *this);
}
bool operator>(const ChunkVersion& otherVersion) const {
return this->_combined > otherVersion._combined;
}
bool operator>=(const ChunkVersion& otherVersion) const {
return this->_combined >= otherVersion._combined;
}
bool operator<(const ChunkVersion& otherVersion) const {
return this->_combined < otherVersion._combined;
}
// Can we write to this data and not have a problem?
bool isWriteCompatibleWith(const ChunkVersion& other) const {
return epoch() == other.epoch() && majorVersion() == other.majorVersion();
}
/**
* Returns true if this version is (strictly) in the same epoch as the other version and
* this version is older. Returns false if we're not sure because the epochs are different
* or if this version is newer.
*/
bool isOlderThan(const ChunkVersion& otherVersion) const {
if (otherVersion._epoch != _epoch)
return false;
if (majorVersion() != otherVersion.majorVersion())
return majorVersion() < otherVersion.majorVersion();
return minorVersion() < otherVersion.minorVersion();
}
void appendToCommand(BSONObjBuilder* out) const {
appendWithField(out, kShardVersionField);
}
/**
* Serializes the version held by this object to 'out' in the form:
* { ..., <field>: [ <combined major/minor>, <OID epoch> ], ... }.
*/
void appendWithField(BSONObjBuilder* out, StringData field) const;
/**
* NOTE: This format is being phased out. Use appendWithField instead.
*
* Serializes the version held by this object to 'out' in the legacy form:
* { ..., <field>: [ <combined major/minor> ], <field>Epoch: [ <OID epoch> ], ... }
*/
void appendLegacyWithField(BSONObjBuilder* out, StringData field) const;
BSONObj toBSON() const;
std::string toString() const;
private:
uint64_t _combined;
OID _epoch;
};
inline std::ostream& operator<<(std::ostream& s, const ChunkVersion& v) {
s << v.toString();
return s;
}
} // namespace mongo
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