blob-storage implementations.

independent.

use "import time" so we can mess with time.time in tests.

non-shared blob directories, you can set a target cache size and the
cache will periodically be reduced to the target size.

To enable blob cache management, a new IBlobStorage method,
openCommittedBlobFile has been added.

defeat FileStorage's index optimization.

data for reading as an ordinary file, rather than as a blob file.
The ordinary file may be used outside the current transaction and
even after the blob's database connection has been closed.

to create configuration files first. This is primarily useful for
exploration and development.

return values.  This in turn simplified the client and server
software.

Added code to select different client and server stubs and input
handlers depening on whether the Z309 or earlier protocols are used.

ZODB 3.8 clients can now talk to ZODB 3.9 servers and the other way
around.

return values.  This in turn simplified the client and server
software.

Added code to select different client and server stubs and input
handlers depening on whether the Z309 or earlier protocols are used.

ZODB 3.8 clients can now talk to ZODB 3.9 servers and the other way
around.

server whose last transaction is older than the last one the client
saw.

cache file open, and preventing it from being cleaned up on windows.

windows and there's something aboyt the way we're setting up arguments
on windows that makes subproccess unhappy.

In the doctest support, save the pids along with adminaddrs and, when
we shutdown a server, wait for it to stop with os.waitpid. This is to
avoid a race where we end up trying and failing to delete the server's
log files before the server has closed them.

windows. Just made the waitpid ignore exceptions. :)

any reason to reraise this.  all we really care about is that we were
able to connect. This was causing spurious errors during tear down.

(Thanks to Patrick Strawderman for spotting a name error here.)

(Thanks to Patrick Strawderman for pointing these out and providing
initial fixes.)

(Thanks to Patrick Strawderman for pointing this out and providing an
initial fix.)

whenever the cache is stale. This is generated before dropping a cache
and starting cold so that an application can take more drastic
measures. The stale-cache event also now has a storage attribute with
the storage that has a stale cache.

cache or the client storage in a valid state.

Also, changed the drop-cache feature to:

- Log a critical message and to
- Publish an event.  Some applications might want to captre the event
  and exit the process or take some drastic action when the cahe needs
  to be dropped.

all but the standard file descriptors.  This fixed a really hard to
debug test failure. (A server started after a client storage was
started had the client storage's cache loc file open, preventing the
client storage from being reopened.)

For starting servers, the storage config not defaults to a simple
file-storage configuration.

Use a simple log file configuration for the storage server rather than
trying to somehow copy the useless test log configuration. This makes
it far more likely that there will be a sever log available when
debugging test failures.

- Include the storage name in all log messages

- Use the standard logging APIs directly, rather than going through an
  intermediate function.

(The storage is also available as "_storage" for backward
compatibility, mainly for test code.)

cleaned up on disconnect.

Also avoid unnecessary iterator_gc calls to the server when there are
no iterators to be cleaned up.

doctests and for wating for a client to disconnect or connect.