HADOOP-17215: Support for conditional overwrite.
Contributed by Sneha Vijayarajan
DETAILS:
This change adds config key "fs.azure.enable.conditional.create.overwrite" with
a default of true. When enabled, if create(path, overwrite: true) is invoked
and the file exists, the ABFS driver will first obtain its etag and then attempt
to overwrite the file on the condition that the etag matches. The purpose of this
is to mitigate the non-idempotency of this method. Specifically, in the event of
a network error or similar, the client will retry and this can result in the file
being created more than once which may result in data loss. In essense this is
like a poor man's file handle, and will be addressed more thoroughly in the future
when support for lease is added to ABFS.
TEST RESULTS:
namespace.enabled=true
auth.type=SharedKey
-------------------
$mvn -T 1C -Dparallel-tests=abfs -Dscale -DtestsThreadCount=8 clean verify
Tests run: 87, Failures: 0, Errors: 0, Skipped: 0
Tests run: 457, Failures: 0, Errors: 0, Skipped: 42
Tests run: 207, Failures: 0, Errors: 0, Skipped: 24
namespace.enabled=true
auth.type=OAuth
-------------------
$mvn -T 1C -Dparallel-tests=abfs -Dscale -DtestsThreadCount=8 clean verify
Tests run: 87, Failures: 0, Errors: 0, Skipped: 0
Tests run: 457, Failures: 0, Errors: 0, Skipped: 74
Tests run: 207, Failures: 0, Errors: 0, Skipped: 140
10 files changed
