James M Leddy authored Aug 23, 2011 and Howard Chu committed Jul 21, 2014

From RFC 2782:

  A client MUST attempt to contact the target host with the
  lowest-numbered priority it can reach.

This patch sorts the DNS SRV records by their priority, and
additionally gives records with a larger weight a higher probability
of appearing earlier. This way, the DNS SRV records are tried in the
order of their priority.

Push modifications into response callback; only execute if
main Add actually succeeded.

Don't pass non-NULL map address unless MDB_FIXEDMAP was used.

This was actually broken by 65e163d2, ITS#6947. Reverting both
of those changes and fixing #6947 again.

Must also set in sub-cursor if deleting entire subDB

Always set the filesize when opening for writes. Otherwise
can't use backups from mdb_copy.

We mainly use Win32 functions, so cannot just use C-runtime strerror
to return error messages. We have to use Win32-specific messages.
Unfortunately, we document the API to return C-runtime error codes,
so we can't just switch to all Win32 error codes.

Off-by-one in end check, would complain on valid input.

persist size changes from env_open() as well. This was the
original behavior.

This reverts commit d8e18551.
And partially reverts mapsize check. Only mapsize increases are relevant.

Set read txn's dbiseqs to env's. Set child txn's dbiseqs to parent's.
Simplify DBI_CHANGED test, no need to check md_name. No-op dbi_close
of already closed handle.

only update dbiseq in dbi_open on write txns

dbiseqs are only checked in write txns so omit from read txns

Use DBI sequence numbers to detect DBIs being closed while in use.

Write decreases too, not just increases. Check for any size change
that was not requested by this process.