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/**
* Copyright (C) 2009-2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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/db/operation_context.h"
#include "mongo/db/storage/mmap_v1/catalog/namespace.h"
#include "mongo/db/storage/mmap_v1/catalog/namespace_details.h"
#include "mongo/stdx/functional.h"
namespace mongo {
/**
* Simple, fixed size hash table used for namespace mapping (effectively the contents of the
* MMAP V1 .ns file). Uses a contiguous block of memory, so you can put it in a memory mapped
* file very easily.
*/
class NamespaceHashTable {
MONGO_DISALLOW_COPYING(NamespaceHashTable);
public:
typedef stdx::function<void(const Namespace& k, NamespaceDetails& v)> IteratorCallback;
/* buf must be all zeroes on initialization. */
NamespaceHashTable(void* buf, int buflen, const char* name);
NamespaceDetails* get(const Namespace& k) const {
bool found;
int i = _find(k, found);
if (found) {
return &_nodes(i).value;
}
return 0;
}
void kill(OperationContext* txn, const Namespace& k) {
bool found;
int i = _find(k, found);
if (i >= 0 && found) {
Node* n = &_nodes(i);
n = txn->recoveryUnit()->writing(n);
n->key.kill();
n->setUnused();
}
}
/** returns false if too full */
bool put(OperationContext* txn, const Namespace& k, const NamespaceDetails& value) {
bool found;
int i = _find(k, found);
if (i < 0)
return false;
Node* n = txn->recoveryUnit()->writing(&_nodes(i));
if (!found) {
n->key = k;
n->hash = k.hash();
} else {
invariant(n->hash == k.hash());
}
n->value = value;
return true;
}
void iterAll(IteratorCallback callback) {
for (int i = 0; i < n; i++) {
if (_nodes(i).inUse()) {
callback(_nodes(i).key, _nodes(i).value);
}
}
}
private:
#pragma pack(1)
struct Node {
int hash;
Namespace key;
NamespaceDetails value;
bool inUse() const {
return hash != 0;
}
void setUnused() {
hash = 0;
}
};
#pragma pack()
static_assert(sizeof(Node) == 628, "sizeof(Node) == 628");
int _find(const Namespace& k, bool& found) const;
Node& _nodes(int i) const {
Node* nodes = (Node*)_buf;
return nodes[i];
}
const char* _name;
void* const _buf;
int n; // number of hashtable buckets
int maxChain;
};
} // namespace mongo
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