The logger class constructor registers itself with the logger registry,
in order to enable dynamically setting log levels. However, since
thread_local variables may be (and are) initialized at the time of first
use, when the program starts up no loggers are registered.
Fix by making loggers global, not thread_local. This requires that the
registry use locking to prevent registration happening on different threads
from corrupting the registry.
Note that technically global variables can also be initialized at the
point of first use, and there is no portable way for classes to self-register.
However this is the best we can do.
Snitch class semantics defined to be per-Node. To make it so we
introduce here a static member in an i_endpoint_snitch class that
has to contain the pointer to the relevant snitch class instance.
Since the snitch contents are not always pure const it has to be per
shard, therefore we'll make it a "distributed". All the I/O is going
to take place on a single shard and if there are changes - they are going
to be propagated to the rest of the shards.
The application is responsible to initialize this distributed<shnitch>
before it's used for the first time.
This patch effectively reverts most of the "locator: futurize
snitch creation" a2594015f9 patch - the part that modifies the
code that was creating the snitch instance. Since snitch is
created explicitly by the application and all the rest of the code
simply assumes that the above global is initialized we won't need
all those changes any more and the code will get back to be nice and simple
as it was before the patch above.
So, to summarize, this patch does the following:
- Reverts the changes introduced by a2594015f9 related to the fact that
every time a replication strategy was created there should have been created
a snitch that would have been stored in this strategy object. More specifically,
methods like keyspace::create_replication_strategy() do not return a future<>
any more and this allows to simplify the code that calls it significantly.
- Introduce the global distributed<snitch_ptr> object:
- It belongs to the i_endpoint_snitch class.
- There has been added a corresponding interface to access both global and
shard-local instances.
- locator::abstract_replication_strategy::create_replication_strategy() does
not accept snitch_ptr&& - it'll get and pass the corresponding shard-local
instance of the snitch to the replication strategy's constructor by itself.
- Adjusted the existing snitch infrastructure to the new semantics:
- Modified the create_snitch() to create and start all per-shard snitch
instances and update the global variable.
- Introduced a static i_endpoint_snitch::stop_snitch() function that properly
stops the global distributed snitch.
- Added the code to the gossiping_property_file_snitch that distributes the
changed data to all per-shard snitch objects.
- Made all existing snitches classes properly maintain their state in order
to be able to shut down cleanly.
- Patched both urchin and cql_query_test to initialize a snitch instance before
all other services.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
New in v6:
- Rebased to the current master.
- Extended a commit message a little - the summary.
New in v5:
- database::create_keyspace(): added a missing _keyspaces.emplace()
New in v4:
- Kept the database::create_keyspace() to return future<> by Glauber's request
and added a description to this method that needs to be changed when Glauber
adds his bits that require this interface.
- Introduce snitch_base class that implements all snitch functionality
except for get_rack() and get_datacenter() methods.
- Requires the inheriting classes to initialize _my_rack and _my_dc fields.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
New in v2:
- Returned copyright lines.
- Make _my_dc and _my_rack a non-optional for now.
- Styling and add an "override" qualifier to virtual functions implementations.
- Move most of snitch_base members into snitch_base.cc.
- snitch_base.hh: Add "Modified by Cloudius Systems" to a license.
- simple_snitch: copyright
- rack_inferring_snitch: copyright
