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211 lines
8.1 KiB
211 lines
8.1 KiB
# Copyright (c) 2014 Palantir Technologies
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#
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# Permission is hereby granted, free of charge, to any person obtaining a copy
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# of this software and associated documentation files (the "Software"), to deal
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# in the Software without restriction, including without limitation the rights
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# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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# copies of the Software, and to permit persons to whom the Software is
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# furnished to do so, subject to the following conditions:
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#
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# The above copyright notice and this permission notice shall be included in
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# all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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# THE SOFTWARE.
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"""Thread safe sqlite3 interface."""
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__author__ = "Shawn Lee"
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__email__ = "shawnl@palantir.com"
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__license__ = "MIT"
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import logging
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try:
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import queue as Queue # module re-named in Python 3
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except ImportError:
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import Queue
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import sqlite3
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import threading
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import time
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import uuid
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LOGGER = logging.getLogger('sqlite3worker')
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class Sqlite3Worker(threading.Thread):
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"""Sqlite thread safe object.
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Example:
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from sqlite3worker import Sqlite3Worker
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sql_worker = Sqlite3Worker("/tmp/test.sqlite")
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sql_worker.execute(
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"CREATE TABLE tester (timestamp DATETIME, uuid TEXT)")
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sql_worker.execute(
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"INSERT into tester values (?, ?)", ("2010-01-01 13:00:00", "bow"))
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sql_worker.execute(
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"INSERT into tester values (?, ?)", ("2011-02-02 14:14:14", "dog"))
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sql_worker.execute("SELECT * from tester")
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sql_worker.close()
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"""
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def __init__(self, file_name, max_queue_size=100, as_dict=False):
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"""Automatically starts the thread.
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Args:
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file_name: The name of the file.
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max_queue_size: The max queries that will be queued.
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as_dict: Return result as a dictionary.
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"""
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threading.Thread.__init__(self)
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self.daemon = True
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self.sqlite3_conn = sqlite3.connect(
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file_name, check_same_thread=False,
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detect_types=sqlite3.PARSE_DECLTYPES)
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if as_dict:
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self.sqlite3_conn.row_factory = dict_factory
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self.sqlite3_cursor = self.sqlite3_conn.cursor()
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self.sql_queue = Queue.Queue(maxsize=max_queue_size)
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self.results = {}
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self.max_queue_size = max_queue_size
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self.exit_set = False
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# Token that is put into queue when close() is called.
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self.exit_token = str(uuid.uuid4())
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self.start()
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self.thread_running = True
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def run(self):
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"""Thread loop.
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This is an infinite loop. The iter method calls self.sql_queue.get()
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which blocks if there are not values in the queue. As soon as values
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are placed into the queue the process will continue.
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If many executes happen at once it will churn through them all before
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calling commit() to speed things up by reducing the number of times
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commit is called.
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"""
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LOGGER.debug("run: Thread started")
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execute_count = 0
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for token, query, values, only_one in iter(self.sql_queue.get, None):
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LOGGER.debug("sql_queue: %s", self.sql_queue.qsize())
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if token != self.exit_token:
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LOGGER.debug("run: %s", query)
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self.run_query(token, query, values, only_one)
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execute_count += 1
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# Let the executes build up a little before committing to disk
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# to speed things up.
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if (
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self.sql_queue.empty() or
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execute_count == self.max_queue_size):
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LOGGER.debug("run: commit")
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self.sqlite3_conn.commit()
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execute_count = 0
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# Only exit if the queue is empty. Otherwise keep getting
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# through the queue until it's empty.
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if self.exit_set and self.sql_queue.empty():
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self.sqlite3_conn.commit()
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self.sqlite3_conn.close()
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self.thread_running = False
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return
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def run_query(self, token, query, values, only_one):
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"""Run a query.
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Args:
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token: A uuid object of the query you want returned.
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query: A sql query with ? placeholders for values.
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values: A tuple of values to replace "?" in query.
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"""
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if query.lower().strip().startswith("select"):
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try:
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self.sqlite3_cursor.execute(query, values)
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if only_one:
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self.results[token] = self.sqlite3_cursor.fetchone()
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else:
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self.results[token] = self.sqlite3_cursor.fetchall()
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except sqlite3.Error as err:
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# Put the error into the output queue since a response
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# is required.
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self.results[token] = (
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"Query returned error: %s: %s: %s" % (query, values, err))
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LOGGER.error(
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"Query returned error: %s: %s: %s", query, values, err)
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else:
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try:
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self.sqlite3_cursor.execute(query, values)
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except sqlite3.Error as err:
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LOGGER.error(
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"Query returned error: %s: %s: %s", query, values, err)
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def close(self):
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"""Close down the thread and close the sqlite3 database file."""
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self.exit_set = True
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self.sql_queue.put((self.exit_token, "", "", ""), timeout=5)
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# Sleep and check that the thread is done before returning.
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while self.thread_running:
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time.sleep(.01) # Don't kill the CPU waiting.
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@property
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def queue_size(self):
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"""Return the queue size."""
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return self.sql_queue.qsize()
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def query_results(self, token):
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"""Get the query results for a specific token.
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Args:
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token: A uuid object of the query you want returned.
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Returns:
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Return the results of the query when it's executed by the thread.
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"""
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delay = .001
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while True:
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if token in self.results:
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return_val = self.results[token]
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del self.results[token]
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return return_val
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# Double back on the delay to a max of 8 seconds. This prevents
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# a long lived select statement from trashing the CPU with this
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# infinite loop as it's waiting for the query results.
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LOGGER.debug("Sleeping: %s %s", delay, token)
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time.sleep(delay)
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if delay < 8:
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delay += delay
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def execute(self, query, values=None, only_one=False):
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"""Execute a query.
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Args:
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query: The sql string using ? for placeholders of dynamic values.
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values: A tuple of values to be replaced into the ? of the query.
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Returns:
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If it's a select query it will return the results of the query.
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"""
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if self.exit_set:
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LOGGER.debug("Exit set, not running: %s", query)
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return "Exit Called"
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LOGGER.debug("execute: %s", query)
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values = values or []
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# A token to track this query with.
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token = str(uuid.uuid4())
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# If it's a select we queue it up with a token to mark the results
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# into the output queue so we know what results are ours.
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if query.lower().strip().startswith("select"):
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self.sql_queue.put((token, query, values, only_one), timeout=5)
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return self.query_results(token)
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else:
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self.sql_queue.put((token, query, values, only_one), timeout=5)
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def dict_factory(cursor, row):
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d = {}
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for idx, col in enumerate(cursor.description):
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d[col[0]] = row[idx]
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return d
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