pgsql: Add lock_timeout configuration parameter.

Add lock_timeout configuration parameter.

This GUC allows limiting the time spent waiting to acquire any one
heavyweight lock.

In support of this, improve the recently-added timeout infrastructure
to permit efficiently enabling or disabling multiple timeouts at once.
That reduces the performance hit from turning on lock_timeout, though
it's still not zero.

Zoltán Böszörményi, reviewed by Tom Lane,
Stephen Frost, and Hari Babu

Branch
------
master

Details
-------
http://git.postgresql.org/pg/commitdiff/d43837d03067487560af481474ae985df894f786

Modified Files
--------------
doc/src/sgml/config.sgml                      |   40 +++-
src/backend/postmaster/autovacuum.c           |   10 +-
src/backend/storage/ipc/standby.c             |   11 +-
src/backend/storage/lmgr/proc.c               |   50 ++++-
src/backend/tcop/postgres.c                   |   17 ++-
src/backend/utils/init/postinit.c             |   18 ++
src/backend/utils/misc/guc.c                  |   11 +
src/backend/utils/misc/postgresql.conf.sample |    1 +
src/backend/utils/misc/timeout.c              |  303 +++++++++++++++++--------
src/bin/pg_dump/pg_backup_archiver.c          |    5 +-
src/bin/pg_dump/pg_dump.c                     |    2 +
src/include/storage/proc.h                    |    5 +-
src/include/utils/timeout.h                   |   35 +++-
src/test/isolation/expected/timeouts.out      |   73 ++++++
src/test/isolation/isolation_schedule         |    1 +
src/test/isolation/specs/timeouts.spec        |   45 ++++
16 files changed, 511 insertions(+), 116 deletions(-)