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63a0502ed1
Before this patch the interaction between the layers above was as follows:
- trace_state was passing the trace event data to a backend object every
time trace() method was called.
- trace_state was passing the session data to a backend object in a destructor.
- A backend object was storing this data in a form of lambda where all data
above was caught in a capture list. This was primarily done in order to
delay the call for make_xxx_mutation(). Lambdas were stored in a map by a session
ID and they were executed when a kick() method was called.
- A tracing::tracing object was periodically calling a kick() method of a
backend that was initiating a write of all pending data to the storage.
All backend methods used in the described above interactions were virtual.
Thereby, for instance, for each and every trace record we were calling a virtual method that was
receiving a significant amount of parameters, store a lambda in a map and return.
This is clearly a suboptimal way of using virtual functions since we prevent a compiler
from inlining an obviously inlinable operations.
This patch changes the interaction scheme to be as follows:
- Trace events and session data are stored and passed around in a form of structs
that hold all relevant information (no more lambdas).
- As long as a trace session is active its data is aggregated inside the corresponding
trace_state object.
- The object containing all records is passed and stored as a lw_shared_ptr to save extra
copies and to shorten capture lists.
- All aggregated data is passed to a tracing::tracing object in a trace_state destructor.
The data is stored in a std::deque in a tracing::tracing object (instead of a map by a session ID).
- A single backend's virtual method call writes all data aggregated so far (kick()
method is not needed any more), every time a write event occurs.
- Backend has only one virtual method now:
- Write a bulk of sessions' data aggregated so far.
- Backend's virtual method receives a records bulk object by reference.
As a result:
- A latency of a single trace event that has no formatting improved from 0.2us to 0.1us.
Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
Scylla
Building Scylla
In addition to required packages by Seastar, the following packages are required by Scylla.
Submodules
Scylla uses submodules, so make sure you pull the submodules first by doing:
git submodule init
git submodule update --recursive
Building and Running Scylla on Fedora
- Installing required packages:
sudo dnf install yaml-cpp-devel lz4-devel zlib-devel snappy-devel jsoncpp-devel thrift-devel antlr3-tool antlr3-C++-devel libasan libubsan gcc-c++ gnutls-devel ninja-build ragel libaio-devel cryptopp-devel xfsprogs-devel numactl-devel hwloc-devel libpciaccess-devel libxml2-devel python3-pyparsing lksctp-tools-devel protobuf-devel protobuf-compiler
- Build Scylla
./configure.py --mode=release --with=scylla --disable-xen
ninja-build build/release/scylla -j2 # you can use more cpus if you have tons of RAM
- 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>
Contributing to Scylla
Do not send pull requests.
Send patches to the mailing list address scylladb-dev@googlegroups.com. Be sure to subscribe.
In order for your patches to be merged, you must sign the Contributor's License Agreement, protecting your rights and ours. See http://www.scylladb.com/opensource/cla/.