DiskCache Development¶
DiskCache development is lead by Grant Jenks <contact@grantjenks.com>.
Collaborators Welcome¶
Search issues or open a new issue to start a discussion around a bug.
Fork the GitHub repository and make your changes in a new branch.
Write a test which shows the bug was fixed.
Send a pull request and message the development lead until its merged and published.
Requests for Contributions¶
Command-line interface. Operations to support: get, set, store, delete, expire, evict, clear, path, check, stats.
Django admin interface for cache stats and interaction.
Cache stampede barrier (source prototype in repo).
API Compatibility
Backend Compatibility
Get the Code¶
DiskCache is actively developed in a GitHub repository.
You can either clone the public repository:
$ git clone https://github.com/grantjenks/python-diskcache.git
Download the tarball:
$ curl -OL https://github.com/grantjenks/python-diskcache/tarball/master
Or, download the zipball:
$ curl -OL https://github.com/grantjenks/python-diskcache/zipball/master
Installing Dependencies¶
Install development dependencies with pip:
$ pip install -r requirements.txt
All packages for running tests will be installed.
Additional packages like pylibmc and redis along with their server
counterparts are necessary for some benchmarks.
Testing¶
DiskCache currently tests against five versions of Python:
CPython 3.5
CPython 3.6
CPython 3.7
CPython 3.8
Testing uses tox. If you don’t want to install all the development requirements, then, after downloading, you can simply run:
$ python setup.py test
The test argument to setup.py will download a minimal testing infrastructure and run the tests.
$ tox
GLOB sdist-make: python-diskcache/setup.py
py27 inst-nodeps: python-diskcache/.tox/dist/diskcache-0.9.0.zip
py27 runtests: PYTHONHASHSEED='3527394681'
py27 runtests: commands[0] | nosetests
.........................................................................
----------------------------------------------------------------------
Ran 98 tests in 29.404s
OK
py34 inst-nodeps: python-diskcache/.tox/dist/diskcache-0.9.0.zip
py34 runtests: PYTHONHASHSEED='3527394681'
py34 runtests: commands[0] | nosetests
.........................................................................
----------------------------------------------------------------------
Ran 98 tests in 22.841s
OK
py35 inst-nodeps: python-diskcache/.tox/dist/diskcache-0.9.0.zip
py35 runtests: PYTHONHASHSEED='3527394681'
py35 runtests: commands[0] | nosetests
.........................................................................
----------------------------------------------------------------------
Ran 98 tests in 23.803s
OK
____________________ summary ____________________
py27: commands succeeded
py34: commands succeeded
py35: commands succeeded
congratulations :)
Coverage testing uses nose:
$ nosetests --cover-erase --with-coverage --cover-package diskcache
.........................................................................
Name Stmts Miss Cover Missing
--------------------------------------------------------
diskcache.py 13 2 85% 9-11
diskcache/core.py 442 4 99% 22-25
diskcache/djangocache.py 43 0 100%
diskcache/fanout.py 66 0 100%
--------------------------------------------------------
TOTAL 564 6 99%
----------------------------------------------------------------------
Ran 98 tests in 28.766s
OK
It’s normal to not see 100% coverage. Some code is specific to the Python runtime.
Stress testing is also based on nose but can be run independently as a
module. Stress tests are kept in the tests directory and prefixed with
stress_test_. Stress tests accept many arguments. Read the help for
details.
$ python -m tests.stress_test_core --help
usage: stress_test_core.py [-h] [-n OPERATIONS] [-g GET_AVERAGE]
[-k KEY_COUNT] [-d DEL_CHANCE] [-w WARMUP]
[-e EXPIRE] [-t THREADS] [-p PROCESSES] [-s SEED]
[--no-create] [--no-delete] [-v EVICTION_POLICY]
optional arguments:
-h, --help show this help message and exit
-n OPERATIONS, --operations OPERATIONS
Number of operations to perform (default: 10000)
-g GET_AVERAGE, --get-average GET_AVERAGE
Expected value of exponential variate used for GET
count (default: 100)
-k KEY_COUNT, --key-count KEY_COUNT
Number of unique keys (default: 10)
-d DEL_CHANCE, --del-chance DEL_CHANCE
Likelihood of a key deletion (default: 0.1)
-w WARMUP, --warmup WARMUP
Number of warmup operations before timings (default:
10)
-e EXPIRE, --expire EXPIRE
Number of seconds before key expires (default: None)
-t THREADS, --threads THREADS
Number of threads to start in each process (default:
1)
-p PROCESSES, --processes PROCESSES
Number of processes to start (default: 1)
-s SEED, --seed SEED Random seed (default: 0)
--no-create Do not create operations data (default: True)
--no-delete Do not delete operations data (default: True)
-v EVICTION_POLICY, --eviction-policy EVICTION_POLICY
If stress exits normally then it worked successfully. Some stress is run by tox and nose but the iteration count is limited. More rigorous testing requires increasing the iteration count to millions. At that level, it’s best to just let it run overnight. Stress testing will stop at the first failure.
Running Benchmarks¶
Running and plotting benchmarks is a two step process. Each is a Python script
in the tests directory. Benchmark scripts are prefixed with benchmark_. For
example:
$ python tests/benchmark_core.py --help
usage: benchmark_core.py [-h] [-p PROCESSES] [-n OPERATIONS] [-r RANGE]
[-w WARMUP]
optional arguments:
-h, --help show this help message and exit
-p PROCESSES, --processes PROCESSES
Number of processes to start (default: 8)
-n OPERATIONS, --operations OPERATIONS
Number of operations to perform (default: 100000)
-r RANGE, --range RANGE
Range of keys (default: 100)
-w WARMUP, --warmup WARMUP
Number of warmup operations before timings (default:
1000)
Benchmark output is stored in text files prefixed with timings_ in the
tests directory. Plotting the benchmarks is done by passing the timings file
as an argument to plot.py.
