diff options
Diffstat (limited to 'external/glim/sqlite.hpp')
| -rw-r--r-- | external/glim/sqlite.hpp | 538 |
1 files changed, 538 insertions, 0 deletions
diff --git a/external/glim/sqlite.hpp b/external/glim/sqlite.hpp new file mode 100644 index 000000000..c7e92ac4a --- /dev/null +++ b/external/glim/sqlite.hpp @@ -0,0 +1,538 @@ +#ifndef GLIM_SQLITE_HPP_ +#define GLIM_SQLITE_HPP_ + +/** + * A threaded interface to <a href="http://sqlite.org/">SQLite</a>. + * This file is a header-only library, + * whose sole dependencies should be standard STL and posix threading libraries. + * You can extract this file out of the "glim" library to include it separately in your project. + * @code +Copyright 2006-2012 Kozarezov Artem Aleksandrovich + +Licensed under the Apache License, Version 2.0 (the "License"); +you may not use this file except in compliance with the License. +You may obtain a copy of the License at + + 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, +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +See the License for the specific language governing permissions and +limitations under the License. + * @endcode + * @file + */ + +#include <stdexcept> +#include <string> +#include <sqlite3.h> +#include <pthread.h> +#include <string.h> // strerror +#include <sys/types.h> // stat +#include <sys/stat.h> // stat +#include <unistd.h> // stat +#include <errno.h> // stat +#include <stdio.h> // snprintf +#include <stdint.h> + +namespace glim { + +class SqliteSession; +class SqliteQuery; + +struct SqliteEx: public std::runtime_error { + SqliteEx (const std::string& what): std::runtime_error (what) {} +}; + +/** + * The database. + * According to sqlite3_open <a href="http://sqlite.org/capi3ref.html#sqlite3_open">documentation</a>, + * only the thread that opened the database can safely access it. This restriction was + * relaxed, as described in the <a href="http://www.sqlite.org/faq.html#q8">FAQ</a> + * (the "Is SQLite threadsafe?" question), so we can use the library from multiple + * threads, but only if no more than one thread at a time accesses the database. + * This restriction is, in fact, beneficial if the database is used from a single application: + * by restricting access to a sigle thread at a time, we effectively avoid all deadlock issues.\n + * This library goals are:\n + * \li to ensure that SQLite is used in a thread-safe way, + * \li to provide additional threaded quirks, such as delayed updates (not implemented). + * + * The library is targeted at SQLite setup which is \b not \c -DTHREADSAFE, + * since this is the default setup on UNIX architectures.\n + * \n + * This file is a header-only library, + * whose sole dependencies should be standard STL and posix threading libraries. + * You can extract this file out of the "glim" library to include it separately in your project.\n + * \n + * This library is targeted at UTF-8 API. There is no plans to support the UTF-16 API.\n + * \n + * See also:\n + * \li http://www.sqlite.org/cvstrac/fileview?f=sqlite/src/server.c\n + * for another way of handling multithreading with SQLite. + */ +class Sqlite { + /// No copying allowed. + Sqlite& operator = (const Sqlite& other) {return *this;} + /// No copying allowed. + Sqlite (const Sqlite& other) = delete; + friend class SqliteSession; + protected: + /// Filename the database was opened with; we need it to reopen the database on fork()s. + /// std::string is used to avoid memory allocation issues. + std::string filename; + ::sqlite3* handler; + ::pthread_mutex_t mutex; + public: + /// Flags for the Sqlite constructor. + enum Flags { + /** + * The file will be checked for existence. + * SqliteEx is thrown if the file is not accessible; + * format of the error description is "$filename: $strerror".\n + * Usage example: \code Sqlite db ("filename", Sqlite::existing); \endcode + */ + existing = 1 + }; + /** + * Opens the database. + * @param filename Database filename (UTF-8). + * @param flags Optional. Currently there is the #existing flag. + * @throws SqliteEx Thrown if we can't open the database. + */ + Sqlite (std::string filename, int flags = 0) { + if (flags & existing) { + // Check if the file exists already. + struct stat st; if (stat (filename.c_str(), &st)) + throw SqliteEx (filename + ": " + ::strerror(errno)); + } + ::pthread_mutex_init (&mutex, NULL); + this->filename = filename; + if (::sqlite3_open(filename.c_str(), &handler) != SQLITE_OK) + throw SqliteEx (std::string("sqlite3_open(") + filename + "): " + ::sqlite3_errmsg(handler)); + } + /** + * Closes the database. + * @throws SqliteEx Thrown if we can't close the database. + */ + ~Sqlite () { + ::pthread_mutex_destroy (&mutex); + if (::sqlite3_close(handler) != SQLITE_OK) + throw SqliteEx (std::string ("sqlite3_close(): ") + ::sqlite3_errmsg(handler)); + } + + Sqlite& exec (const char* query); + /** + * Invokes `exec` on `query.c_str()`. + * Example:\code + * glim::Sqlite sqlite (":memory:"); + * for (std::string pv: {"page_size = 4096", "secure_delete = 1"}) sqlite->exec2 ("PRAGMA " + pv); \endcode + */ + template <typename StringLike> Sqlite& exec2 (StringLike query) {return exec (query.c_str());} +}; + +/** + * A single thread session with Sqlite. + * Only a sigle thread at a time can have an SqliteSession, + * all other threads will wait, in the SqliteSession constructor, + * till the active session is either closed or destructed. + */ +class SqliteSession { + /// No copying allowed. + SqliteSession& operator = (const SqliteSession& other) {return *this;} + /// No copying allowed. + SqliteSession(SqliteSession& other): db (NULL) {} + protected: + Sqlite* db; + public: + /** + * Locks the database. + * @throws SqliteEx if a mutex error occurs. + */ + SqliteSession (Sqlite* sqlite): db (sqlite) { + int err = ::pthread_mutex_lock (&(db->mutex)); + if (err != 0) throw SqliteEx (std::string ("error locking the mutex: ") + ::strerror(err)); + } + /** + * A shorter way to construct query from the session. + * Usage example: \code ses.query(S("create table test (i integer)")).step() \endcode + * @see SqliteQuery#qstep + */ + template <typename T> + SqliteQuery query (T t); + /// Automatically unlocks the database. + /// @see close + ~SqliteSession () {close();} + /** + * Unlock the database. + * It is safe to call this method multiple times.\n + * You must not use the session after it was closed.\n + * All resources allocated within this session must be released before the session is closed. + * @throws SqliteEx if a mutex error occurs. + */ + void close () { + if (db == NULL) return; + int err = ::pthread_mutex_unlock (&(db->mutex)); + db = NULL; + if (err != 0) throw SqliteEx (std::string ("error unlocking the mutex: ") + ::strerror(err)); + } + /// True if the \c close method has been already called on this SqliteSession. + bool isClosed () const { + return db == NULL; + } + /** + * This class can be used in place of the SQLite handler. + * Make sure you've released any resources thus manually acquired before this SqliteSession is closed. + * Usage example: + * @code + * glim::Sqlite db (":memory:"); + * glim::SqliteSession ses (&db); + * sqlite3_exec (ses, "PRAGMA page_size = 4096;", NULL, NULL, NULL); + * @endcode + */ + operator ::sqlite3* () const {return db->handler;} +}; + +/** + * Execute the given query, throwing SqliteEx on failure.\n + * Example:\code + * glim::Sqlite sqlite (":memory:"); + * sqlite.exec ("PRAGMA page_size = 4096") .exec ("PRAGMA secure_delete = 1"); \endcode + */ +inline Sqlite& Sqlite::exec (const char* query) { + SqliteSession ses (this); // Maintains the locks. + char* errmsg = NULL; ::sqlite3_exec (handler, query, NULL, NULL, &errmsg); + if (errmsg) throw SqliteEx (std::string ("Sqlite::exec, error in query (") + query + "): " + errmsg); + return *this; +} + +/** + * Wraps the sqlite3_stmt; will prepare it, bind values, query and finalize. + */ +class SqliteQuery { + protected: + ::sqlite3_stmt* statement; + SqliteSession* session; + int bindCounter; + /// -1 if statement isn't DONE. + int mChanges; + void prepare (SqliteSession* session, char const* query, int queryLength) { + ::sqlite3* handler = *session; + if (::sqlite3_prepare_v2 (handler, query, queryLength, &statement, NULL) != SQLITE_OK) + throw SqliteEx (std::string(query, queryLength) + ": " + ::sqlite3_errmsg(handler)); + } + /** Shan't copy. */ + SqliteQuery (const SqliteQuery& other) = delete; + public: + SqliteQuery (SqliteQuery&& rvalue) { + statement = rvalue.statement; + session = rvalue.session; + bindCounter = rvalue.bindCounter; + mChanges = rvalue.mChanges; + rvalue.statement = nullptr; + } + /** + * Prepares the query. + * @throws SqliteEx if sqlite3_prepare fails; format of the error message is "$query: $errmsg". + */ + SqliteQuery (SqliteSession* session, char const* query, int queryLength) + : statement (NULL), session (session), bindCounter (0), mChanges (-1) { + prepare (session, query, queryLength); + } + /** + * Prepares the query. + * @throws SqliteEx if sqlite3_prepare fails; format of the error message is "$query: $errmsg". + */ + SqliteQuery (SqliteSession* session, std::pair<char const*, int> query) + : statement (NULL), session (session), bindCounter (0), mChanges (-1) { + prepare (session, query.first, query.second); + } + /** + * Prepares the query. + * @throws SqliteEx if sqlite3_prepare fails; format of the error message is "$query: $errmsg". + */ + SqliteQuery (SqliteSession* session, std::string query) + : statement (NULL), session (session), bindCounter (0), mChanges (-1) { + prepare (session, query.c_str(), query.length()); + } + /** + * Release resources. + * @see http://sqlite.org/capi3ref.html#sqlite3_finalize + */ + ~SqliteQuery () { + if (statement) ::sqlite3_finalize (statement); + } + + /// Call this (followed by the #step) if you need the query to be re-executed. + /// @see http://sqlite.org/capi3ref.html#sqlite3_reset + SqliteQuery& reset () { + bindCounter = 0; + mChanges = -1; + ::sqlite3_reset (statement); + return *this; + } + + /// Synonym for #step. + bool next () {return step();} + /** + * Invokes sqlite3_step. + * @return \c true if there was a row fetched successfully, \c false if there is no more rows. + * @see http://sqlite.org/capi3ref.html#sqlite3_step + */ + bool step () { + if (mChanges >= 0) {mChanges = 0; return false;} + int ret = ::sqlite3_step (statement); + if (ret == SQLITE_ROW) return true; + if (ret == SQLITE_DONE) { + mChanges = ::sqlite3_changes (*session); + return false; + } + throw SqliteEx (std::string(::sqlite3_errmsg(*session))); + } + /** + * Perform #step and throw an exception if #step has returned \c false. + * Usage example: + * \code (ses.query(S("select count(*) from test where idx = ?")) << 12345).qstep().intAt(1) \endcode + */ + SqliteQuery& qstep () { + if (!step()) + throw SqliteEx (std::string("qstep: no rows returned / affected")); + return *this; + } + /** + * Invokes a DML query and returns the number of rows affected. + * Example: \code + * int affected = (ses.query(S("update test set count = count + ? where id = ?")) << 1 << 9).ustep(); + * \endcode + * @see http://sqlite.org/capi3ref.html#sqlite3_step + */ + int ustep () { + int ret = ::sqlite3_step (statement); + if (ret == SQLITE_DONE) { + mChanges = ::sqlite3_changes (*session); + return mChanges; + } + if (ret == SQLITE_ROW) return 0; + throw SqliteEx (std::string(::sqlite3_errmsg(*session))); + } + + /** + * The number of rows changed by the query. + * Providing the query was a DML (Data Modification Language), + * returns the number of rows updated.\n + * If the query wasn't a DML, returned value is undefined.\n + * -1 is returned if the query wasn't executed, or after #reset.\n + * Example: \code + * SqliteQuery query (&ses, S("update test set count = count + ? where id = ?")); + * query.bind (1, 1); + * query.bind (2, 9); + * query.step (); + * int affected = query.changes (); + * \endcode + * @see #ustep + */ + int changes () {return mChanges;} + + /** + * The integer value of the given column. + * @param column 1-based. + * @see http://sqlite.org/capi3ref.html#sqlite3_column_text + */ + int intAt (int column) { + return ::sqlite3_column_int (statement, --column); + } + + /** + * The integer value of the given column. + * @param column 1-based. + * @see http://sqlite.org/capi3ref.html#sqlite3_column_text + */ + sqlite3_int64 int64at (int column) { + return ::sqlite3_column_int64 (statement, --column); + } + + /** + * The floating point number from the given column. + * @param column 1-based. + * @see http://sqlite.org/capi3ref.html#sqlite3_column_text + */ + double doubleAt (int column) { + return ::sqlite3_column_double (statement, --column); + } + + /** + * Return the column as UTF-8 characters, which can be used until the next #step. + * @param column 1-based. + * @see http://sqlite.org/capi3ref.html#sqlite3_column_text + */ + std::pair<char const*, int> charsAt (int column) { + return std::pair<char const*, int> ((char const*) ::sqlite3_column_text (statement, column-1), + ::sqlite3_column_bytes (statement, column-1)); + } + + /** + * Return the column as C++ string (UTF-8). + * @param column 1-based. + */ + std::string stringAt (int column) { + return std::string ((char const*) ::sqlite3_column_text (statement, column-1), + ::sqlite3_column_bytes (statement, column-1)); + } + + /** + * The type of the column. + * SQLITE_INTEGER, SQLITE_FLOAT, SQLITE_TEXT, SQLITE_BLOB or SQLITE_NULL. + * @param column 1-based. + * @see http://sqlite.org/capi3ref.html#sqlite3_column_text + */ + int typeAt (int column) { + return ::sqlite3_column_type (statement, --column); + } + + /** + * Binds a value using one of the bind methods. + */ + template<typename T> + SqliteQuery& operator << (T value) { + return bind (++bindCounter, value); + } + /** + * Binds a value using the named parameter and one of the bind methods. + * @throws SqliteEx if the name could not be found. + * @see http://sqlite.org/capi3ref.html#sqlite3_bind_parameter_index + */ + template<typename T> + SqliteQuery& bind (char const* name, T value) { + int index = ::sqlite3_bind_parameter_index (statement, name); + if (index == 0) + throw SqliteEx (std::string ("No such parameter in the query: ") + name); + return bind (index, value); + } + + /** + * Bind a string to the query. + * @param transient must be true, if lifetime of the string might be shorter than that of the query. + */ + SqliteQuery& bind (int index, const char* text, int length, bool transient = false) { + if (::sqlite3_bind_text (statement, index, text, length, + transient ? SQLITE_TRANSIENT : SQLITE_STATIC) != SQLITE_OK) + throw SqliteEx (std::string (::sqlite3_errmsg (*session))); + return *this; + } + /** + * Bind a string to the query. + * @param transient must be true, if lifetime of the string might be shorter than that of the query. + */ + SqliteQuery& bind (int index, std::pair<const char*, int> text, bool transient = false) { + if (::sqlite3_bind_text (statement, index, text.first, text.second, + transient ? SQLITE_TRANSIENT : SQLITE_STATIC) != SQLITE_OK) + throw SqliteEx (std::string (::sqlite3_errmsg (*session))); + return *this; + } + /** + * Bind a string to the query. + * @param transient must be true, if lifetime of the string might be shorter than that of the query. + */ + SqliteQuery& bind (int index, const std::string& text, bool transient = true) { + if (::sqlite3_bind_text (statement, index, text.data(), text.length(), + transient ? SQLITE_TRANSIENT : SQLITE_STATIC) != SQLITE_OK) + throw SqliteEx (std::string (::sqlite3_errmsg (*session))); + return *this; + } + /** + * Bind an integer to the query. + */ + SqliteQuery& bind (int index, int value) { + if (::sqlite3_bind_int (statement, index, value) != SQLITE_OK) + throw SqliteEx (std::string (::sqlite3_errmsg (*session))); + return *this; + } + /** + * Bind an 64-bit integer to the query. + */ + SqliteQuery& bind (int index, sqlite3_int64 value) { + if (::sqlite3_bind_int64 (statement, index, value) != SQLITE_OK) + throw SqliteEx (std::string (::sqlite3_errmsg (*session))); + return *this; + } +}; + +/** + * Version of SqliteQuery suitable for using SQLite in parallel with other processes. + * Will automatically handle the SQLITE_SCHEMA error + * and will automatically repeat attempts after SQLITE_BUSY, + * but it requires that the query string supplied + * is constant and available during the SqliteParQuery lifetime. + * Error messages, contained in exceptions, may differ from SqliteQuery by containing the query + * (for example, the #step method will throw "$query: $errmsg" instead of just "$errmsg"). + */ +class SqliteParQuery: public SqliteQuery { + protected: + char const* query; + int queryLength; + int repeat; + int wait; + public: + /** + * Prepares the query. + * @param repeat the number of times we try to repeat the query when SQLITE_BUSY is returned. + * @param wait how long, in milliseconds (1/1000 of a second) we are to wait before repeating. + * @throws SqliteEx if sqlite3_prepare fails; format of the error message is "$query: $errmsg". + */ + SqliteParQuery (SqliteSession* session, char const* query, int queryLength, int repeat = 90, int wait = 20) + : SqliteQuery (session, query, queryLength) { + this->query = query; + this->queryLength = queryLength; + this->repeat = repeat; + this->wait = wait; + } + /** + * Prepares the query. + * @param query the SQL query together with its length. + * @param repeat the number of times we try to repeat the query when SQLITE_BUSY is returned. + * @param wait how long, in milliseconds (1/1000 of a second) we are to wait before repeating. + * @throws SqliteEx if sqlite3_prepare fails; format of the error message is "$query: $errmsg". + */ + SqliteParQuery (SqliteSession* session, std::pair<char const*, int> query, int repeat = 90, int wait = 20) + : SqliteQuery (session, query) { + this->query = query.first; + this->queryLength = query.second; + this->repeat = repeat; + this->wait = wait; + } + + bool next () {return step();} + bool step () { + if (mChanges >= 0) {mChanges = 0; return false;} + repeat: + int ret = ::sqlite3_step (statement); + if (ret == SQLITE_ROW) return true; + if (ret == SQLITE_DONE) { + mChanges = ::sqlite3_changes (*session); + return false; + } + if (ret == SQLITE_SCHEMA) { + ::sqlite3_stmt* old = statement; + prepare (session, query, queryLength); + ::sqlite3_transfer_bindings(old, statement); + ::sqlite3_finalize (old); + goto repeat; + } + if (ret == SQLITE_BUSY) for (int repeat = this->repeat; ret == SQLITE_BUSY && repeat >= 0; --repeat) { + //struct timespec ts; ts.tv_sec = 0; ts.tv_nsec = wait * 1000000; // nan is 10^-9 of sec. + //while (::nanosleep (&ts, &ts) == EINTR); + ::sqlite3_sleep (wait); + ret = ::sqlite3_step (statement); + } + throw SqliteEx (std::string(query, queryLength) + ::sqlite3_errmsg(*session)); + } +}; + +template <typename T> +SqliteQuery SqliteSession::query (T t) { + return SqliteQuery (this, t); +} + +}; // namespace glim + +#endif // GLIM_SQLITE_HPP_ |