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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 18:24:20 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-27 18:24:20 +0000 |
commit | 483eb2f56657e8e7f419ab1a4fab8dce9ade8609 (patch) | |
tree | e5d88d25d870d5dedacb6bbdbe2a966086a0a5cf /doc/dev/context.rst | |
parent | Initial commit. (diff) | |
download | ceph-upstream.tar.xz ceph-upstream.zip |
Adding upstream version 14.2.21.upstream/14.2.21upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'doc/dev/context.rst')
-rw-r--r-- | doc/dev/context.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/doc/dev/context.rst b/doc/dev/context.rst new file mode 100644 index 00000000..1a2b2cbf --- /dev/null +++ b/doc/dev/context.rst @@ -0,0 +1,20 @@ +============= + CephContext +============= + +A CephContext represents a single view of the Ceph cluster. It comes complete +with a configuration, a set of performance counters (PerfCounters), and a +heartbeat map. You can find more information about CephContext in +src/common/ceph_context.h. + +Generally, you will have only one CephContext in your application, called +g_ceph_context. However, in library code, it is possible that the library user +will initialize multiple CephContexts. For example, this would happen if he +called rados_create more than once. + +A ceph context is required to issue log messages. Why is this? Well, without +the CephContext, we would not know which log messages were disabled and which +were enabled. The dout() macro implicitly references g_ceph_context, so it +can't be used in library code. It is fine to use dout and derr in daemons, but +in library code, you must use ldout and lderr, and pass in your own CephContext +object. The compiler will enforce this restriction. |