2011053183
Summary: Use the smart view technique from [1] to avoid quadratic behavior of left-nested binds in the continuation of Blocked results. This makes the seql benchmark linear (and quite fast). (See before-and-after benchmark results in P20020178) [1] http://dl.acm.org/citation.cfm?id=2784743 Test Plan: Ran the Haxl core tests with `fbmake runtests`. Also compared the microbenchmarks in MonadBench. (see P20020178) End-to-end test results for top 25 contexts: https://www.facebook.com/pxlcld/mPXZ https://www.facebook.com/pxlcld/mPZ2 https://www.facebook.com/pxlcld/mPZ0 https://www.facebook.com/pxlcld/mPZ1 Based on those, not sure what to do. It does seem like a very slight improvement, but not strictly improving. Thoughts? Reviewed By: smarlow@fb.com Subscribers: ldbrandy, kjm, jlengyel, memo, watashi, smarlow, akr, bnitka, jcoens FB internal diff: D2438616 Tasks: 8432911 Signature: t1:2438616:1442568800:bf2d1a18819c0ceeb6ea097379ec4bbc6364c0c2 |
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| example | ||
| Haxl | ||
| tests | ||
| .gitignore | ||
| .travis.yml | ||
| haxl.cabal | ||
| LICENSE | ||
| logo.png | ||
| logo.svg | ||
| PATENTS | ||
| readme.md | ||
| Setup.hs | ||
Haxl
Haxl is a Haskell library that simplifies access to remote data, such as databases or web-based services. Haxl can automatically
- batch multiple requests to the same data source,
- request data from multiple data sources concurrently,
- cache previous requests.
Having all this handled for you behind the scenes means that your data-fetching code can be much cleaner and clearer than it would otherwise be if it had to worry about optimizing data-fetching. We'll give some examples of how this works in the pages linked below.
There are two Haskell packages here:
haxl: The core Haxl frameworkhaxl-facebook(in example/facebook): An (incomplete) example data source for accessing the Facebook Graph API
To use Haxl in your own application, you will likely need to build one or more
data sources: the thin layer between Haxl and the data that you want
to fetch, be it a database, a web API, a cloud service, or whatever.
The haxl-facebook package shows how we might build a Haxl data
source based on the existing fb package for talking to the Facebook
Graph API.
Where to go next?
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The Story of Haxl explains how Haxl came about at Facebook, and discusses our particular use case.
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An example Facebook data source walks through building an example data source that queries the Facebook Graph API concurrently.
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The N+1 Selects Problem explains how Haxl can address a common performance problem with SQL queries by automatically batching multiple queries into a single query, completely invisibly to the programmer.
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Haxl Documentation on Hackage.
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There is no Fork: An Abstraction for Efficient, Concurrent, and Concise Data Access, our paper on Haxl, accepted for publication at ICFP'14.