> On Feb. 25, 2015, 10:25 a.m., Timothy Chen wrote:
> > src/slave/containerizer/fetcher.cpp, line 103
> > <https://reviews.apache.org/r/30774/diff/19/?file=875881#file875881line103>
> >
> >     How about introducing a Cache namespace, so then we can just do 
> > Fetcher::Cache::recover, Fetcher::Cache::clean, etc?

There is already a cache class. The shape of this code is an artefact of not 
injecting slaveId and flags. We will clean this up when we refactor for the 
latter.


> On Feb. 25, 2015, 10:25 a.m., Timothy Chen wrote:
> > src/slave/containerizer/fetcher.cpp, line 516
> > <https://reviews.apache.org/r/30774/diff/19/?file=875881#file875881line516>
> >
> >     Shouldn't you also log the error too?

This probably does not interrupt or change any user-driven action. It might, 
but it also might not.


> On Feb. 25, 2015, 10:25 a.m., Timothy Chen wrote:
> > src/slave/flags.hpp, line 108
> > <https://reviews.apache.org/r/30774/diff/19/?file=875884#file875884line108>
> >
> >     So the default value is actually not a recommended practice? Why set 
> > the default to that then?

So we can run tests. I have adjusted the doc as indicated above.


- Bernd


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On Feb. 25, 2015, 9:54 a.m., Bernd Mathiske wrote:
> 
> -----------------------------------------------------------
> This is an automatically generated e-mail. To reply, visit:
> https://reviews.apache.org/r/30774/
> -----------------------------------------------------------
> 
> (Updated Feb. 25, 2015, 9:54 a.m.)
> 
> 
> Review request for mesos, Adam B, Benjamin Hindman, Till Toenshoff, and 
> Timothy Chen.
> 
> 
> Bugs: MESOS-2057, MESOS-2069, MESOS-2070, MESOS-2072, MESOS-2073, and 
> MESOS-2074
>     https://issues.apache.org/jira/browse/MESOS-2057
>     https://issues.apache.org/jira/browse/MESOS-2069
>     https://issues.apache.org/jira/browse/MESOS-2070
>     https://issues.apache.org/jira/browse/MESOS-2072
>     https://issues.apache.org/jira/browse/MESOS-2073
>     https://issues.apache.org/jira/browse/MESOS-2074
> 
> 
> Repository: mesos
> 
> 
> Description
> -------
> 
> Almost all of the functionality in epic MESOS-336. Downloaded files from 
> CommandInfo::URIs can now be cached in a cache directory designated by a 
> slave flag. This only happens when asked for by an extra flag in the URI and 
> is thus backwards-compatible. The cache has a size limit also given by a new 
> slave flag. Cache-resident files are evicted as necessary to make space for 
> newly fetched ones. Concurrent attempts to cache the same URI leads to only 
> one download. The fetcher program remains external for safety reasons, but is 
> now augmented with more elaborate parameters packed into a JSON object to 
> implement specific fetch actions for all of the above. Additional testing 
> includes fetching from (mock) HDFS and coverage of the new features.
> 
> 
> Diffs
> -----
> 
>   docs/fetcher.md PRE-CREATION 
>   include/mesos/fetcher/fetcher.proto 
> facb87b92bf3194516f636dcc348e136af537721 
>   include/mesos/mesos.proto 507845c493f65e154214fc7e562206e452990469 
>   src/Makefile.am d372404d84c9ac0bc49da7407ad366701b9586a6 
>   src/hdfs/hdfs.hpp 968545d9af896f3e72e156484cc58135405cef6b 
>   src/launcher/fetcher.cpp 5b2d86d1867b25bf71461fd73df91b089002325b 
>   src/slave/constants.hpp 12d6e92b814076fd423a7738e030dc6ce6954761 
>   src/slave/containerizer/docker.hpp 70114dcef7a416ae904e95eb9ce365bcd866aebc 
>   src/slave/containerizer/docker.cpp 813ddf8c98622748b2da1b739bf122387abc4c79 
>   src/slave/containerizer/fetcher.hpp 
> bfd98dbe16e2bd5df3e2c8e9b10e303654f33446 
>   src/slave/containerizer/fetcher.cpp 
> 6e6bce08d76bb8a5813c905e3ffeff9b2411fd6d 
>   src/slave/containerizer/mesos/containerizer.hpp 
> 074a2d82dcd882e52f8cd62ed7493295596acb26 
>   src/slave/containerizer/mesos/containerizer.cpp 
> d5b90d12d63becfeb4c3efa9c6f5d826417f582c 
>   src/slave/flags.hpp ddb32593566b71bcf0b66adeeb889e43ef911084 
>   src/slave/slave.cpp ec7ec1356e745bb07484ae1755c9183b038043b3 
>   src/tests/docker_containerizer_tests.cpp 
> 8b212d4e6ed5a179ebadce1bdbbf3edde87d706c 
>   src/tests/fetcher_cache_tests.cpp PRE-CREATION 
>   src/tests/fetcher_tests.cpp fcbf7ad912f0b1b3d106a75a9dcb8213a0c69c07 
>   src/tests/mesos.hpp 60c70043c8266a422ffa03ab5a949da0bc822124 
>   src/tests/mesos.cpp d76ed8c837da162d782de84e935fe8e11e01d6b0 
>   src/tests/mock_hadoop.sh PRE-CREATION 
> 
> Diff: https://reviews.apache.org/r/30774/diff/
> 
> 
> Testing
> -------
> 
> make check
> 
> --- longer Description: ---
> 
> -Replaces all other reviews for the fetcher cache except those related to 
> stout: 30006, 30033, 30034, 30036, 30037, 30039, 30124, 30173, 30614, 30616, 
> 30618, 30621, 30626. See descriptions of those. In dependency order:
> 
> 30033: Removes the fetcher env tests since these won't be needed any more 
> when the fetcher uses JSON in a single env var as a parameter. They never 
> tested anything that won't be covered by other tests anyway.
> 
> 30034: Makes the code structure of all fetcher tests the same. Instead of 
> calling the run method of the fetcher directly, calling through fetch(). Also 
> removes all uses of I/O redirection, which is not really needed for 
> debugging, and thus the next patch can refactor fetch() and run(). (The 
> latter comes in two varieties, which complicates matters without much 
> benefit.)
> 
> 30036: Extends the CommandInfo::URI protobuf with a boolean "caching" field 
> that will later cause fetcher cache actions. Also introduces the notion of a 
> cache directory to the fetcher info protobuf. And then propagates these 
> additions throughout the rest of the code base where applicable. This 
> includes passing the slave ID all the way down to the place where the cache 
> dir name is constructed.
> 
> 30037: Extends the fetcher info protobuf with "actions" (fetch directly 
> bypassing the cache, fetch through the cache, retrieve from the cache). 
> Switches the basis for dealing with uris to "items", which contain the uri, 
> the action, and potentially a cache file name. Refactors fetch() and run(), 
> so there is only one of each. Introduces about half of the actual cache 
> logic, including a hashmap of cache file objects for bookkeeping and basic 
> operations on it. 
> 
> 30039: Enables fetcher cache actions in the mesos fetcher program.
> 
> 30006: Enables concurrent downloading into the fetcher cache. Reuse of 
> download results in the cache when multiple fetcher runs occur concurrently. 
> 
> 30614: This is to ensure that all this refactoring of fetcher code has not 
> broken HDFS fetching. Adds a test that exercises the C++ code paths in Mesos 
> and mesos-fetcher related to fetching from HDFS. Uses a mock HDFS client 
> written in bash that acts just like a real "hadoop" command if used in the 
> right limited way.
> 
> 30124: Inserted fetcher cache zap upon slave startup, recovery and shutdown. 
> This implements recovery in an acceptable, yet most simple way.
> 
> 30173: Created fetcher cache tests. Adds a new test source file containing a 
> test fixture and tests to find out if the fetcher cache works with a variety 
> of settings.
> 
> 30616: Adds hdfs::du() which calls "hadoop fs -du -h" and returns a string 
> that contains the file size for the URI passed as argument. This is needed to 
> determine the size of a file on HDFS before downloading it to the fetcher 
> cache (to ensure there is enough space).
> 
> 30621: Refactored URI type separation in mesos-fetcher. Moved the URI type 
> separation code (distinguishes http, hdfs, local copying, etc.) from 
> mesos-fetcher to the fetcher process/actor, since it is going to be reused by 
> download size queries when we introduce fetcher cache management. Also 
> factored out URI validation, which will be used the same way by mesos-fetcher 
> and the fetcher process/actor.
> 
> 30626: Fetcher cache eviction. This happens when the cache does not have 
> enough space to accomodate upcoming downloads to the cache. Necessary 
> provisions included here:
> - mesos-fetcher does not run until evictions have been successful
> - Cache space is reserved while (async) waiting for eviction to succeed. If 
> it fails, the reservation gets undone.
> - Reservations can be partly from available space, partly from evictions. All 
> math included :-)
> - To find out how much space is needed, downloading has a prelude in which we 
> query the download size from the URI. This works for all URI types that 
> mesos-fetcher currently supports, including http and hdfs.
> - Size-determination requests are now synchronized, too. Only one per URI in 
> play happens.
> - There is cleanup code for all kinds of error situations. At the very end of 
> the fetch attempt, each list is processed for undoing things like space 
> reservations and eviction disabling.
> - Eviction gets disabled for URIs that are currently in use, i.e. the related 
> cache files are. We use reference counting for this, since there may be 
> concurrent fetch attempts using the same cache files.
> 
> 
> Thanks,
> 
> Bernd Mathiske
> 
>

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