jgit/tst at 73a432514936fcee1386b37a0d60dcd913706bd1 - jgit

纯java实现的git操作库。

Christian Halstrick 11d24e6844 Fix FileSnapshot.isModified FileSnapshot.isModified may have reported a file to be clean although it was actually dirty. Imagine you have a FileSnapshot on file f. lastmodified and lastread are both t0. Now time is t1 and you 1) modify the file 2) update the FileSnapshot of the file (lastModified=t1, lastRead=t1) 3) modify the file again 4) wait 3 seconds 5) ask the Filesnapshot whether the file is dirty or not. It erroneously answered it's clean. Any file which has been modified longer than 2.5 seconds ago was reported to be clean. As the test shows that's not always correct. The real-world problem fixed by this change is the following: * A gerrit server using JGit to serve git repositories is processing fetch requests while simultaneously a native git garbage collection runs on the repo. * At time t1 native git writes temporary files in the pack folder setting the mtime of the pack folder to t1. * A fetch request causes JGit to search for new packfiles and JGit remembers this scan in a Filesnapshot on the packs folder. Since the gc is not finished JGit doesn't see any new packfiles. * The fetch is processed and the gc ends while the filesystem timer is still t1. GC writes a new packfile and deletes the old packfile. * 3 seconds later another request arrives. JGit does not yet know about the new packfile but is also not rescanning the pack folder because it cached that the last scan happened at time t1 and pack folder's mtime is also t1. Now JGit will not be able to resolve any object contained in this new pack. This behavior may be persistent if objects referenced by the ref/meta/config branch are affected so gerrit can't read permissions stored in the refs/meta/config branch anymore and will not allow any pushes anymore. The pack folder will not change its mtime and therefore no rescan will take place. Change-Id: I3efd0ccffeb97b01207dc3e7a6b85c6b06928fad Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>	8 years ago
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org/eclipse/jgit	Fix FileSnapshot.isModified	8 years ago

Christian Halstrick 11d24e6844 Fix FileSnapshot.isModified

FileSnapshot.isModified may have reported a file to be clean although it
was actually dirty.

Imagine you have a FileSnapshot on file f. lastmodified and lastread are
both t0. Now time is t1 and you
1) modify the file
2) update the FileSnapshot of the file (lastModified=t1, lastRead=t1)
3) modify the file again
4) wait 3 seconds
5) ask the Filesnapshot whether the file is dirty or not. It erroneously
answered it's clean.

Any file which has been modified longer than 2.5 seconds ago was
reported to be clean. As the test shows that's not always correct.

The real-world problem fixed by this change is the following:
* A gerrit server using JGit to serve git repositories is processing
fetch requests while simultaneously a native git garbage collection
runs on the repo.
* At time t1 native git writes temporary files in the pack folder
setting the mtime of the pack folder to t1.
* A fetch request causes JGit to search for new packfiles and JGit
remembers this scan in a Filesnapshot on the packs folder. Since the gc
is not finished JGit doesn't see any new packfiles.
* The fetch is processed and the gc ends while the filesystem timer is
still t1. GC writes a new packfile and deletes the old packfile.
* 3 seconds later another request arrives. JGit does not yet know about
the new packfile but is also not rescanning the pack folder because it
cached that the last scan happened at time t1 and pack folder's mtime is
also t1. Now JGit will not be able to resolve any object contained in
this new pack. This behavior may be persistent if objects referenced by
the ref/meta/config branch are affected so gerrit can't read permissions
stored in the refs/meta/config branch anymore and will not allow any
pushes anymore. The pack folder will not change its mtime and therefore
no rescan will take place.

Change-Id: I3efd0ccffeb97b01207dc3e7a6b85c6b06928fad
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

8 years ago

org/eclipse/jgit

Fix FileSnapshot.isModified

8 years ago