- also clean up some cruft remaining from per-thread connection cache

Remove CachedConnectionPerThread per-thread pooling mechanism in favor of a fixed pool with default maximum of 5 connections

- delegating methods left behind

This reverts commit 3d2512d38d2e28b3ea669139f7c7b0307522aa72.

- Also carry allow_concurrency value through to connection adapter
  (for postgresql)

- use new active support Module#synchronize
- allow_concurrency now switches between a null monitor and a
  regular monitor (defaulting to null monitor to avoid overhead)

- Distinguis meaning of "active_connections" to always mean connections
  associated with the current thread

So far so good, tests still run clean. Next steps: synchronize connection pool access
and modification, and change allow_concurrency to simply switch a real lock for a
null lock.

This is more friendly to JRuby/JDBC adapters (with names like 'jdbcmysql')
and leaves the door open to alternate implementations of adapters in the
future.

Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#871 state:committed]

Signed-off-by: NMichael Koziarski <michael@koziarski.com>
[#931 state:committed]

Signed-off-by: NMichael Koziarski <michael@koziarski.com>

Signed-off-by: NJoshua Peek <josh@joshpeek.com>

Signed-off-by: NPratik Naik <pratiknaik@gmail.com>

Please install render_component plugin from http://github.com/rails/render_component/tree/master
if your application uses this functionality.

[#407 state:resolved]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

[#501 state:resolved]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>

[#831 state:resolved]
Signed-off-by: NJeremy Kemper <jeremy@bitsweat.net>