Check for ext3/ext4 fs, then check kernel version.

This reverts commit e95c9231.

Revert "Hack for potential ext3/ext4 corruption issue"

This reverts commit 91155b9d.

Use regular fsync() if we think this commit grew the DB file.

We actually compare the new key against the last key, to prevent
corruption.

The concurrency restriction is on threads within a single process.
Multiple processes can use mdb_dbi_open without affecting each other.

More fallout from 4d02c741:
Don't modify another thread's write txn. Reinit me_txn0 fully.

Howard Chu authored Oct 08, 2014 and Hallvard Furuseth committed Dec 01, 2014

fstat returns -1, not an errno. Move code into its own function
for reuse.

Howard Chu authored Oct 04, 2014 and Hallvard Furuseth committed Dec 01, 2014

More fallout from 4d02c741

Jean-Christophe DUBOIS authored Oct 03, 2014 and Hallvard Furuseth committed Dec 01, 2014

Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>

Leonid Yuriev authored Sep 05, 2014 and Hallvard Furuseth committed Dec 01, 2014

TRIVIA - lmdb: clean testdb-dir while "make test".

When reusing the main write txn

Free writer txn on env_close

Change retry to num times 60.  Testing shows that on a known dataset, this has the same growth behavior as 2.4.39, while num times 20 resulted in significant growth.

Leave it in main env struct, it doesn't need to be rolled back
with nested txns.

Don't walk the readers table unless we really need to.