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 <time.h>
#include "lmdb.h"
#include "libp2p/utils/logger.h"
#include "ipfs/repo/fsrepo/lmdb_datastore.h"
#include "varint.h"
/**
* Build a "value" section for a datastore record
* @param timestamp the timestamp
* @param data the data (usually a base32 of the cid hash)
* @param data_length the length of data
* @param result the resultant data object
* @param result_size the size of the result
* @returns true(1) on success, otherwise 0
*/
int repo_fsrepo_lmdb_build_record(const unsigned long long timestamp, const uint8_t *data, size_t data_length, uint8_t **result, size_t *result_size) {
// turn timestamp into varint
uint8_t ts_varint[8];
size_t num_bytes;
if (varint_encode(timestamp, &ts_varint[0], 8, &num_bytes) == NULL) {
return 0;
}
// make new structure
*result = (uint8_t *) malloc(num_bytes + data_length);
if (*result == NULL) {
return 0;
}
memcpy(*result, ts_varint, num_bytes);
memcpy(&(*result)[num_bytes], data, data_length);
*result_size = data_length + num_bytes;
return 1;
}
/**
* read a "value" section from a datastore record.
* @param data what we read from the datastore
* @param data_length the length of what we read from the datastore
* @param timestamp the timestamp that was read from the datastore
* @param record_pos where the data starts (without the timestamp)
* @param record_size the size of the data section of the record
* @returns true(1) on success, false(0) otherwise
*/
int repo_fsrepo_lmdb_parse_record(uint8_t *data, size_t data_length, unsigned long long *timestamp, uint8_t *record_pos, size_t *record_size) {
size_t varint_size = 0;
*timestamp = varint_decode(data, data_length, &varint_size);
record_pos = &data[varint_size];
return 1;
}
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/***
* 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) {
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
if (mdb_txn_begin(mdb_env, NULL, 0, &mdb_txn) != 0)
return 0;
if (mdb_dbi_open(mdb_txn, DATASTORE_DB, MDB_DUPSORT | MDB_CREATE, &mdb_dbi) != 0) {
mdb_txn_commit(mdb_txn);
return 0;
}
// prepare data
db_key.mv_size = key_size;
db_key.mv_data = (char*)key;
if (mdb_get(mdb_txn, mdb_dbi, &db_key, &db_value) != 0) {
mdb_txn_commit(mdb_txn);
return 0;
}
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// the data from the database includes a timestamp. We'll need to strip it off.
unsigned long long timestamp;
uint8_t *pos = NULL;
size_t size = 0;
if (!repo_fsrepo_lmdb_parse_record(db_key.mv_data, db_key.mv_size, &timestamp, pos, &size)) {
mdb_txn_commit(mdb_txn);
return 0;
}
// Was it too big to fit in the buffer they sent?
if (size > max_data_size) {
mdb_txn_commit(mdb_txn);
return 0;
}
// set return values
memcpy(data, pos, size);
(*data_size) = size;
// clean up
mdb_txn_commit(mdb_txn);
return 1;
}
/***
* Write a journal record
* @param mbd_txn the transaction
* @param timestamp the timestamp
* @param hash the hash
* @param hash_size the size of the hash
* @returns true(1) on success, false(0) otherwise
*/
int repo_fsrepo_lmdb_journal_add(MDB_txn* mdb_txn, unsigned long long timestamp, const uint8_t *hash, size_t hash_size) {
MDB_dbi mdb_dbi;
struct MDB_val db_key;
struct MDB_val db_value;
libp2p_logger_debug("lmdb_datastore", "journal add timestamp: %llu.\n", timestamp);
// build the record, which is a timestamp as a key, a byte that is the pin flag, and the hash as the value
uint8_t time_varint[8];
size_t time_varint_size = 0;
varint_encode(timestamp, &time_varint[0], 8, &time_varint_size);
libp2p_logger_debug("lmdb_datastore", "journal add varint size: %lu.\n", (unsigned long)time_varint_size);
size_t record_size = hash_size + 1;
uint8_t record[record_size];
record[0] = 1;
memcpy(&record[1], hash, hash_size);
// open the journal table
if (mdb_dbi_open(mdb_txn, JOURNAL_DB, MDB_DUPSORT | MDB_CREATE, &mdb_dbi) != 0) {
return 0;
}
// write the record
db_key.mv_size = time_varint_size;
db_key.mv_data = time_varint;
db_value.mv_size = record_size;
db_value.mv_data = record;
if (mdb_put(mdb_txn, mdb_dbi, &db_key, &db_value, 0) == 0) {
return 0;
}
return 1;
}
/**
* Get the current time UTC
* @returns number of seconds since epoch in UTC
*/
unsigned long long lmdb_datastore_gmt_time() {
time_t local = time(NULL);
struct tm *gmt = gmtime(&local);
return (unsigned long long)mktime(gmt);
}
/**
* 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, DATASTORE_DB, MDB_DUPSORT | MDB_CREATE, &mdb_dbi);
if (retVal != 0)
return 0;
// add the timestamp
unsigned long long timestamp = lmdb_datastore_gmt_time();
uint8_t *record;
size_t record_size;
repo_fsrepo_lmdb_build_record(timestamp, data, data_size, &record, &record_size);
// prepare data
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db_key.mv_size = key_size;
db_key.mv_data = (char*)key;
// write
db_value.mv_size = record_size;
db_value.mv_data = record;
retVal = mdb_put(mdb_txn, mdb_dbi, &db_key, &db_value, MDB_NODUPDATA | MDB_NOOVERWRITE);
if (retVal == 0) {
// the normal case
repo_fsrepo_lmdb_journal_add(mdb_txn, timestamp, key, key_size);
retVal = 1;
} else {
if (retVal == MDB_KEYEXIST) // We tried to add a key that already exists. Skip.
retVal = 1;
else
retVal = 0;
}
// cleanup
free(record);
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;
if (mdb_env_create(&mdb_env) < 0) {
mdb_env_close(mdb_env);
return 0;
}
// at most, 2 databases will be opened. The datastore and the journal.
MDB_dbi dbs = 2;
if (mdb_env_set_maxdbs(mdb_env, dbs) != 0) {
mdb_env_close(mdb_env);
return 0;
}
// open the environment
if (mdb_env_open(mdb_env, datastore->path, 0, S_IRWXU) < 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;
}
/***
* Create a new cursor on the datastore database
* @param datastore the place to store the cursor
* @returns true(1) on success, false(0) otherwise
*/
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int repo_fsrepo_lmdb_cursor_open(struct Datastore* datastore) {
if (datastore->handle != NULL) {
MDB_env* mdb_env = (MDB_env*)datastore->handle;
MDB_dbi mdb_dbi;
if (datastore->cursor == NULL ) {
datastore->cursor = malloc(sizeof(struct lmdb_trans_cursor));
struct lmdb_trans_cursor* cursor = (struct lmdb_trans_cursor*)datastore->cursor;
// open transaction
if (mdb_txn_begin(mdb_env, NULL, 0, &cursor->transaction) != 0)
return 0;
MDB_txn* mdb_txn = (MDB_txn*)cursor->transaction;
if (mdb_dbi_open(mdb_txn, DATASTORE_DB, MDB_DUPSORT | MDB_CREATE, &mdb_dbi) != 0) {
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mdb_txn_commit(mdb_txn);
return 0;
}
// open cursor
if (mdb_cursor_open(mdb_txn, mdb_dbi, &cursor->cursor) != 0) {
mdb_txn_commit(mdb_txn);
return 0;
}
return 1;
}
}
return 0;
}
/***
* Get a record using a cursor
* @param key the key from the record
* @param key_length the length of the key
* @param value the value of the record
* @param value_length the length of the value
* @param CURSOR_FIRST or CURSOR_NEXT
* @param datastore holds the reference to the opened cursor
* @returns true(1) on success, false(0) otherwise
*/
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int repo_fsrepo_lmdb_cursor_get(unsigned char** key, int* key_length,
unsigned char** value, int* value_length,
enum DatastoreCursorOp op, struct Datastore* datastore)
{
if (datastore->cursor != NULL) {
struct lmdb_trans_cursor* tc = (struct lmdb_trans_cursor*)datastore->cursor;
MDB_val mdb_key;
MDB_val mdb_value;
MDB_cursor_op co = MDB_FIRST;
if (op == CURSOR_FIRST)
co = MDB_FIRST;
else if (op == CURSOR_NEXT)
co = MDB_NEXT;
if (mdb_cursor_get(tc->cursor, &mdb_key, &mdb_value, co) != 0) {
return 0;
}
*key = (unsigned char*)malloc(mdb_key.mv_size);
memcpy(*key, mdb_key.mv_data, mdb_key.mv_size);
*key_length = mdb_key.mv_size;
if (value != NULL) { // don't do this if a null is passed in, time saver
*value = (unsigned char*)malloc(mdb_value.mv_size);
memcpy(*value, mdb_value.mv_data, mdb_value.mv_size);
*value_length = mdb_value.mv_size;
}
return 1;
}
return 0;
}
/**
* Close an existing cursor
* @param datastore the context
* @returns true(1) on success
*/
int repo_fsrepo_lmdb_cursor_close(struct Datastore* datastore) {
if (datastore->cursor != NULL) {
struct lmdb_trans_cursor* cursor = (struct lmdb_trans_cursor*)datastore->cursor;
if (cursor->cursor != NULL) {
mdb_cursor_close(cursor->cursor);
mdb_txn_commit(cursor->transaction);
free(cursor);
return 1;
}
free(cursor);
}
return 0;
}
/***
* 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;
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datastore->datastore_cursor_open = &repo_fsrepo_lmdb_cursor_open;
datastore->datastore_cursor_get = &repo_fsrepo_lmdb_cursor_get;
datastore->datastore_cursor_close = &repo_fsrepo_lmdb_cursor_close;
datastore->cursor = NULL;
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) {
#ifdef __MINGW32__
return mkdir(datastore->path) == 0;
#else
return mkdir(datastore->path, S_IRWXU) == 0;
#endif
}