gvfs-helper: add gvfs.fallback and unit tests #665
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@derrickstolee I took your #664 and added new unit tests. Hopefully, it all makes sense. I debated putting the config lookup in gvfs-helper.exe, rather than in the client code, but decided that was more risk than I wanted (not that it was hard, but that it would change the historical default behavior, since gvfs-helper.exe does not have fallback turned on and only does it when requested, so it felt kinda backwards to move the decision at this point.) |
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dscho
approved these changes
Jul 1, 2024
| stop_gvfs_protocol_server && | ||
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| grep -q "error: get: (http:503)" OUT.stderr && | ||
| verify_connection_count 3 |
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Clever, the connection count is 6 with the fall-back, and 3 without it. I had to puzzle about the difference for a bit because the test cases are so nearly identical that I suspect that it might make for a fine addition to the commit message to explain this fine point?
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@jeffhostetler thank you so much for taking the time to add the tests. This will be an invaluable source of documentation for future changes to the |
Construct 2 new unit tests to explicitly verify the use of `--fallback` and `--no-fallback` arguments to `gvfs-helper`. When a cache-server is enabled, `gvfs-helper` will try to fetch objects from it rather than the origin server. If the cache-server fails (and all cache-server retry attempts have been exhausted), `gvfs-helper` can optionally "fallback" and try to fetch the objects from the origin server. (The retry logic is also applied to the origin server, if the origin server fails on the first request.) Add new unit tests to verify that `gvfs-helper` respects both the `--max-retries` and `--[no-]fallback` arguments. We use the "http_503" mayhem feature of the `test_gvfs_protocol` server to force a 503 response on all requests to the cache-server and the origin server end-points. We can then count the number of connection requests that `gvfs-helper` makes to the server and confirm both the per-server retries and whether fallback was attempted. Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>
By default, GVFS Protocol-enabled Scalar clones will fall back to the origin server if there is a network issue with the cache servers. However (and especially for the prefetch endpoint) this may be a very expensive operation for the origin server, leading to the user being throttled. This shows up later in cases such as 'git push' or other web operations. To avoid this, create a new config option, 'gvfs.fallback', which defaults to true. When set to 'false', pass '--no-fallback' from the gvfs-helper client to the child gvfs-helper server process. This will allow users who have hit this problem to avoid it in the future. In case this becomes a more widespread problem, engineering systems can enable the config option more broadly. Enabling the config will of course lead to immediate failures for users, but at least that will help diagnose the problem when it occurs instead of later when the throttling shows up and the server load has already passed, damage done. Signed-off-by: Derrick Stolee <stolee@gmail.com>
Create new `cache_http_503` mayhem method where only the cache server sends a 503. The normal `http_503` directs both cache and origin server to send 503s. This will be used to help test fallback. Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>
Signed-off-by: Jeff Hostetler <jeffhostetler@github.com>
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I just added enhanced comments in-line in the test script and in the commit messages. |
Thank you! Please ignore the test failure, this is my mistake. |
@jeffhostetler actually, if I could get your review of #666, that would be nice... |
derrickstolee
approved these changes
Jul 1, 2024
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Thanks for writing these tests, @jeffhostetler! I have a lot more confidence in the change, now.
…er-fallback-config Let's include #666 to let the PR builds pass. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
derrickstolee
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dscho
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By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
dscho
added a commit
that referenced
this pull request
Jul 17, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
dscho
added a commit
that referenced
this pull request
Jul 17, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
dscho
added a commit
that referenced
this pull request
Jul 18, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
mjcheetham
pushed a commit
that referenced
this pull request
Jul 23, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
dscho
added a commit
that referenced
this pull request
Jul 25, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
mjcheetham
pushed a commit
that referenced
this pull request
Jul 29, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
dscho
added a commit
that referenced
this pull request
Sep 18, 2024
By default, GVFS Protocol-enabled Scalar clones will fall back to the
origin server if there is a network issue with the cache servers.
However (and especially for the prefetch endpoint) this may be a very
expensive operation for the origin server, leading to the user being
throttled. This shows up later in cases such as 'git push' or other web
operations.
To avoid this, create a new config option, 'gvfs.fallback', which
defaults to true. When set to 'false', pass '--no-fallback' from the
gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the
future. In case this becomes a more widespread problem, engineering
systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users,
but at least that will help diagnose the problem when it occurs instead
of later when the throttling shows up and the server load has already
passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
---
* [x] This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
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By default, GVFS Protocol-enabled Scalar clones will fall back to the origin server if there is a network issue with the cache servers. However (and especially for the prefetch endpoint) this may be a very expensive operation for the origin server, leading to the user being throttled. This shows up later in cases such as 'git push' or other web operations.
To avoid this, create a new config option, 'gvfs.fallback', which defaults to true. When set to 'false', pass '--no-fallback' from the gvfs-helper client to the child gvfs-helper server process.
This will allow users who have hit this problem to avoid it in the future. In case this becomes a more widespread problem, engineering systems can enable the config option more broadly.
Enabling the config will of course lead to immediate failures for users, but at least that will help diagnose the problem when it occurs instead of later when the throttling shows up and the server load has already passed, damage done.
This change only applies to interactions with Azure DevOps and the
GVFS Protocol.
GVFS Protocol.