Run Mongo "In Memory" for Faster Tests

mongo_fast.sh

#!/bin/sh

# if you run this for anything other than local tests you are making poor
# choices. also, make sure you use safe=True / wc=1 in your tests, or you'll
# get consistency issues

mongod --nojournal --noprealloc --smallfiles --dbpath /Volumes/RAM\ Disk/

ramdisk.py

#!/usr/bin/env python

# This creates a ram disk for OS X located at /Volumes/RAM Disk.
# Because it's in memory, it is nice for mongo tests -- both for
# speed and cleanroom. Although your tests should clean up too...

import os
import subprocess
import time


class RamDisk(object):

    def __init__(self, name, size):
        self._dev_path = None
        self._disk_path = "/Volumes/%s" % (name)
        self._disk_name = name
        self._disk_size = int(size)

    def _mount(self):
        command = [
            "hdiutil", "attach", "-nomount",
            "ram://%d" % (self._disk_size)
        ]
        disk_proc = subprocess.Popen(command, stdout=subprocess.PIPE)
        return_code = disk_proc.wait()
        if return_code != 0:
            raise Exception(disk_proc.stdout.read())
        self._dev_path = disk_proc.stdout.read().strip()

        command = [
            "diskutil", "erasevolume", "HFS+",
            self._disk_name, self._dev_path
        ]
        mount_proc = subprocess.Popen(command, stdout=subprocess.PIPE)
        return_code = mount_proc.wait()
        if return_code != 0:
            raise Exception(mount_proc.stdout.read())

    def _unmount(self):
        path = self._dev_path or self._disk_path
        command = ["hdiutil", "detach", path]
        disk_proc = subprocess.Popen(command, stdout=subprocess.PIPE)
        return_code = disk_proc.wait()
        if return_code != 0:
            raise Exception(disk_proc.stdout.read())

    def wait(self):
        while True:
            try:
                time.sleep(3)
            except KeyboardInterrupt:
                break

    def __enter__(self):
        if os.path.exists(self._disk_path):
            self._unmount()
        self._mount()
        return self

    def __exit__(self, *args, **kwargs):
        print "Unmounting RAM Disk..."
        self._unmount()


def main():
    size = 4194304
    with RamDisk("RAM Disk", size) as ramdisk:
        print "RAM Disk mounted... (CTRL-C to kill)"
        ramdisk.wait()


if __name__ == "__main__":
    main()