mirror of
https://github.com/scylladb/scylladb.git
synced 2026-06-01 12:36:56 +00:00
9000626647
Previously it was the responsibility of the layer above (multishard combining reader) to pause readers, which happened via an explicit `pause()` call. This proved to be a very bad design as we kept finding spots where the multishard reader should have paused the reader to avoid potential deadlocks (due to starved reader concurrency semaphores), but didn't. This commit moves the responsibility of pausing the reader into the shard reader. The reader is now kept in a paused state, except when it is actually used (a `fill_buffer()` or `fast_forward_to()` call is executing). This is fully transparent to the layer above. As a side note, the shard reader now also hides when the reader is created. This also used to be the responsibility of the multishard reader, and although it caused no problems so far, it can be considered a leak of internal details. The shard reader now automatically creates the remote reader on the first time it is attempted to be used. The code has been reorganized, such that there is now a clear separation of responsibilities. The multishard combining reader handles the combining of the output of the shard readers, as well as issuing read-aheads. The shard reader handles read-ahead and creating the remote reader when needed, as well as transferring the results of remote reads to the "home" shard. The remote reader (`shard_reader::remote_reader`, new in this patch) handles pausing-resuming as well as recreating the reader after it was evicted. Layers don't access each other's internals (like they used to). After this commit, the reader passed to `destroy_reader()` will always be in paused state.
Scylla
Quick-start
$ git submodule update --init --recursive
$ sudo ./install-dependencies.sh
$ ./configure.py --mode=release
$ ninja-build -j4 # Assuming 4 system threads.
$ ./build/release/scylla
$ # Rejoice!
Please see HACKING.md for detailed information on building and developing Scylla.
Note: GCC >= 8.1.1 is require to compile Scylla.
Note: See frozen toolchain for a way to build and run on an older distribution.
Running Scylla
- Run Scylla
./build/release/scylla
- run Scylla with one CPU and ./tmp as data directory
./build/release/scylla --datadir tmp --commitlog-directory tmp --smp 1
- For more run options:
./build/release/scylla --help
Building Fedora RPM
As a pre-requisite, you need to install Mock on your machine:
# Install mock:
sudo yum install mock
# Add user to the "mock" group:
usermod -a -G mock $USER && newgrp mock
Then, to build an RPM, run:
./dist/redhat/build_rpm.sh
The built RPM is stored in /var/lib/mock/<configuration>/result directory.
For example, on Fedora 21 mock reports the following:
INFO: Done(scylla-server-0.00-1.fc21.src.rpm) Config(default) 20 minutes 7 seconds
INFO: Results and/or logs in: /var/lib/mock/fedora-21-x86_64/result
Building Fedora-based Docker image
Build a Docker image with:
cd dist/docker
docker build -t <image-name> .
Run the image with:
docker run -p $(hostname -i):9042:9042 -i -t <image name>