Manual compaction returns error if auto-compact is already running

[ashvindersingh]

Found on build 1.2.1-10
Sync Gateway: 1.2.1.4
Using Mac OS-X (el-capitan) liteserv client

Steps:

• Setup and install sync-gateway-tests. https://github.com/couchbaselabs/sync-gateway-tests
• git checkout ios_forestdb_support
• add following environment variables in your shell:

export STORAGE=ForestDB
export SYNCGATE_PATH=/your/path/to/bin/sync_gateway
export LITESERV_PATH=/your/path/to/couchbase-lite-macosx-enterprise_1.2.1-10/LiteServ

• Run script from sync-gateway-tests as follows:

node tests/cbl-database.js

Test script line: https://github.com/couchbaselabs/sync-gateway-tests/blob/master/tests/cbl-database.js#L217

Get the following warnings:
https://gist.github.com/ashvindersingh/f884882f8fb7595da79304aae5409541#file-forestdb_cbl_database-js-logs-L42

https://gist.github.com/ashvindersingh/f884882f8fb7595da79304aae5409541#file-forestdb_cbl_database-js-logs-L72

[snej]

Manual compaction isn't necessary with ForestDB, but of course it should still work. The error is WARNING: ForestDB error: file handle is busy (-23) — it may be that fdb_compact doesn't work if there are multiple handles open on the database. I'll ask.

[snej]

Aha, here's a note from the doc-comment for fdb_compact:

 * Also note that if a given ForestDB file is currently being compacted by the
 * compaction daemon, then FDB_RESULT_FILE_IS_BUSY is returned to the caller.

So it sounds like ForestDB's auto-compact was already in progress when the manual compact was requested.

To fix this, we can either (a) ignore that error code, or (b) handle it by waiting for the background compaction to complete before returning.

[snej]

(To be specific, this should be fixed in CBForest itself.)

[snej]

Merged to dev branch; closing.