The way the registry was previously written if two concurrent uploads
of the same blob were happening one would fail to grab the lock and then
return early. The uploading client would then immediately HEAD the blob
and if it did so quickly enough would get a short size or 404. To avoid
this we need the upload to continue until all concurrent uploads are
complete.
To make this happen we treat upload chunks separately per upload so that
separate uploads cannot overwrite the chunks once they are moved to the
blob directory. We end up moving the chunks to the blob directory in
upload specific locations to facilitate this. Once that is done we can
atomically update the actual blob data from the chunks. In the
filesystem driver we concatenate the chunks into the blob then
atomically rename the result into its final blob/data location. This
ensures that we only ever return valid HEAD info for a blob, and that it
is only requested by the client once it exists.
This should be safe because the objects are hashsum addresses which
means their contents should be identical. If we end up moving one copy
into place then another atomically they will always have the same data
and size.
These logs from an OpenDev test job seem to capture this in action:
# First upload is completing and grabs the lock
2022-02-25 21:28:14,514 INFO registry.api: [u: 935f8eddbb9a4dab8dd8cc45ce7f9384] Upload final chunk _local opendevorg/gerrit digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
2022-02-25 21:28:14,576 DEBUG registry.storage: [u: 935f8eddbb9a4dab8dd8cc45ce7f9384] Locked digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
# Second upload attempts to complete but ends early without the lock
2022-02-25 21:28:15,517 INFO registry.api: [u: e817d8fd6c464f80bf405581e580cbab] Upload final chunk _local opendevorg/gerrit digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
2022-02-25 21:28:15,578 WARNING registry.storage: [u: e817d8fd6c464f80bf405581e580cbab] Failed to obtain lock(1) on digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
2022-02-25 21:28:15,588 INFO registry.api: [u: e817d8fd6c464f80bf405581e580cbab] Upload complete _local opendevorg/gerrit digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
2022-02-25 21:28:15,589 INFO cherrypy.access.140551593545056: ::ffff:172.17.0.1 - - [25/Feb/2022:21:28:15] "PUT /v2/opendevorg/gerrit/blobs/uploads/e817d8fd6c464f80bf405581e580cbab?digest=sha256%3A0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 HTTP/1.1" 201 - "" "docker/20.10.12 go/go1.16.12 git-commit/459d0df kernel/5.4.0-100-generic os/linux arch/amd64 UpstreamClient(Docker-Client/20.10.12 \(linux\))"
# Second upload completion triggers the HEAD requests that is either a
# 404 or short read. This causes the second upload client to error.
2022-02-25 21:28:15,605 INFO registry.api: Head blob _local opendevorg/gerrit sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 not found
2022-02-25 21:28:15,607 INFO cherrypy.access.140551593545056: ::ffff:172.17.0.1 - - [25/Feb/2022:21:28:15] "HEAD /v2/opendevorg/gerrit/blobs/sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 HTTP/1.1" 404 735 "" "docker/20.10.12 go/go1.16.12 git-commit/459d0df kernel/5.4.0-100-generic os/linux arch/amd64 UpstreamClient(Docker-Client/20.10.12 \(linux\))"
# Now first upload has completed and the HEAD request by the first
# upload client is successful
2022-02-25 21:28:18,898 INFO registry.api: [u: 935f8eddbb9a4dab8dd8cc45ce7f9384] Upload complete _local opendevorg/gerrit digest sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343
2022-02-25 21:28:18,898 INFO cherrypy.access.140551593545056: ::ffff:172.17.0.1 - - [25/Feb/2022:21:28:18] "PUT /v2/opendevorg/gerrit/blobs/uploads/935f8eddbb9a4dab8dd8cc45ce7f9384?digest=sha256%3A0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 HTTP/1.1" 201 - "" "docker/20.10.12 go/go1.16.12 git-commit/459d0df kernel/5.4.0-100-generic os/linux arch/amd64 UpstreamClient(Docker-Client/20.10.12 \(linux\))"
2022-02-25 21:28:18,915 INFO registry.api: Head blob _local opendevorg/gerrit sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 size 54917164
2022-02-25 21:28:18,916 INFO cherrypy.access.140551593545056: ::ffff:172.17.0.1 - - [25/Feb/2022:21:28:18] "HEAD /v2/opendevorg/gerrit/blobs/sha256:0c6b8ff8c37e92eb1ca65ed8917e818927d5bf318b6f18896049b5d9afc28343 HTTP/1.1" 200 54917164 "" "docker/20.10.12 go/go1.16.12 git-commit/459d0df kernel/5.4.0-100-generic os/linux arch/amd64 UpstreamClient(Docker-Client/20.10.12 \(linux\))"
Change-Id: Ibdf1ca554756af61247d705b2ea3cf85c39c2b83
4213b96d3a