c-ipfs/repo/fsrepo/lmdb_datastore.c

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/***
* Here are the wrappers for the lightning database
* NOTE: In this implementation, the database will contain the base32 encoded value
* of the multihash key if the file exists on disk.
*/
#include <stdlib.h>
#include <sys/stat.h>
#include <errno.h>
#include <string.h>
#include "lmdb.h"
#include "ipfs/repo/fsrepo/lmdb_datastore.h"
/***
* retrieve a record from the database and put in a pre-sized buffer
* @param key the key to look for
* @param key_size the length of the key
* @param data the data that is retrieved
* @param max_data_size the length of the data buffer
* @param data_size the length of the data that was found in the database
* @param datastore where to look for the data
* @returns true(1) on success
*/
int repo_fsrepo_lmdb_get(const char* key, size_t key_size, unsigned char* data, size_t max_data_size, size_t* data_size, const struct Datastore* datastore) {
int retVal;
MDB_txn* mdb_txn;
MDB_dbi mdb_dbi;
struct MDB_val db_key;
struct MDB_val db_value;
MDB_env* mdb_env = (MDB_env*)datastore->handle;
if (mdb_env == NULL)
return 0;
// open transaction
retVal = mdb_txn_begin(mdb_env, NULL, 0, &mdb_txn);
if (retVal != 0)
return 0;
retVal = mdb_dbi_open(mdb_txn, NULL, MDB_DUPSORT, &mdb_dbi);
if (retVal != 0) {
mdb_txn_commit(mdb_txn);
return 0;
}
// prepare data
db_key.mv_size = key_size;
db_key.mv_data = (char*)key;
retVal = mdb_get(mdb_txn, mdb_dbi, &db_key, &db_value);
if (retVal != 0) {
mdb_dbi_close(mdb_env, mdb_dbi);
mdb_txn_commit(mdb_txn);
return 0;
}
// now copy the data
if (db_value.mv_size > max_data_size) {
mdb_dbi_close(mdb_env, mdb_dbi);
mdb_txn_commit(mdb_txn);
return 0;
}
// set return values
memcpy(data, db_value.mv_data, db_value.mv_size);
(*data_size) = db_value.mv_size;
// clean up
mdb_dbi_close(mdb_env, mdb_dbi);
mdb_txn_commit(mdb_txn);
return 1;
}
/**
* Write data to the datastore with the specified key
* @param key the key
* @param key_size the length of the key
* @param data the data to be written
* @param data_size the length of the data to be written
* @param datastore the datastore to write to
* @returns true(1) on success
*/
int repo_fsrepo_lmdb_put(unsigned const char* key, size_t key_size, unsigned char* data, size_t data_size, const struct Datastore* datastore) {
int retVal;
MDB_txn* mdb_txn;
MDB_dbi mdb_dbi;
struct MDB_val db_key;
struct MDB_val db_value;
MDB_env* mdb_env = (MDB_env*)datastore->handle;
if (mdb_env == NULL)
return 0;
// open transaction
retVal = mdb_txn_begin(mdb_env, NULL, 0, &mdb_txn);
if (retVal != 0)
return 0;
retVal = mdb_dbi_open(mdb_txn, NULL, MDB_DUPSORT, &mdb_dbi);
if (retVal != 0)
return 0;
// prepare data
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db_key.mv_size = key_size;
db_key.mv_data = (char*)key;
// write
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db_value.mv_size = data_size;
db_value.mv_data = data;
retVal = mdb_put(mdb_txn, mdb_dbi, &db_key, &db_value, MDB_NODUPDATA | MDB_NOOVERWRITE);
if (retVal == 0) // the normal case
retVal = 1;
else {
if (retVal == MDB_KEYEXIST) // We tried to add a key that already exists. Skip.
retVal = 1;
else
retVal = 0;
}
// cleanup
mdb_dbi_close(mdb_env, mdb_dbi);
mdb_txn_commit(mdb_txn);
return retVal;
}
/**
* Open an lmdb database with the given parameters.
* Note: for now, the parameters are not used
* @param argc number of parameters in the following array
* @param argv an array of parameters
*/
int repo_fsrepro_lmdb_open(int argc, char** argv, struct Datastore* datastore) {
// create environment
struct MDB_env* mdb_env;
int retVal = mdb_env_create(&mdb_env);
if (retVal < 0) {
mdb_env_close(mdb_env);
return 0;
}
// open the environment
retVal = mdb_env_open(mdb_env, datastore->path, 0, S_IRWXU);
if (retVal < 0) {
mdb_env_close(mdb_env);
return 0;
}
datastore->handle = (void*)mdb_env;
return 1;
}
/***
* Close an LMDB database
* NOTE: for now, argc and argv are not used
* @param argc number of parameters in the argv array
* @param argv parameters to be passed in
* @param datastore the datastore struct that contains information about the opened database
*/
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int repo_fsrepo_lmdb_close(struct Datastore* datastore) {
struct MDB_env* mdb_env = (struct MDB_env*)datastore->handle;
mdb_env_close(mdb_env);
return 1;
}
/***
* Places the LMDB methods into the datastore's function pointers
* @param datastore the datastore to fill
* @returns true(1) on success;
*/
int repo_fsrepo_lmdb_cast(struct Datastore* datastore) {
datastore->datastore_open = &repo_fsrepro_lmdb_open;
datastore->datastore_close = &repo_fsrepo_lmdb_close;
datastore->datastore_put = &repo_fsrepo_lmdb_put;
datastore->datastore_get = &repo_fsrepo_lmdb_get;
return 1;
}
/***
* Creates the directory
* @param datastore contains the path that needs to be created
* @returns true(1) on success
*/
int repo_fsrepo_lmdb_create_directory(struct Datastore* datastore) {
return mkdir(datastore->path, S_IRWXU) == 0;
}