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author | Qiaowei Ren <qiaowei.ren@intel.com> | 2018-01-04 13:43:33 +0800 |
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committer | Qiaowei Ren <qiaowei.ren@intel.com> | 2018-01-05 11:59:39 +0800 |
commit | 812ff6ca9fcd3e629e49d4328905f33eee8ca3f5 (patch) | |
tree | 04ece7b4da00d9d2f98093774594f4057ae561d4 /src/ceph/doc/dev/context.rst | |
parent | 15280273faafb77777eab341909a3f495cf248d9 (diff) |
initial code repo
This patch creates initial code repo.
For ceph, luminous stable release will be used for base code,
and next changes and optimization for ceph will be added to it.
For opensds, currently any changes can be upstreamed into original
opensds repo (https://github.com/opensds/opensds), and so stor4nfv
will directly clone opensds code to deploy stor4nfv environment.
And the scripts for deployment based on ceph and opensds will be
put into 'ci' directory.
Change-Id: I46a32218884c75dda2936337604ff03c554648e4
Signed-off-by: Qiaowei Ren <qiaowei.ren@intel.com>
Diffstat (limited to 'src/ceph/doc/dev/context.rst')
-rw-r--r-- | src/ceph/doc/dev/context.rst | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/src/ceph/doc/dev/context.rst b/src/ceph/doc/dev/context.rst new file mode 100644 index 0000000..1a2b2cb --- /dev/null +++ b/src/ceph/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. |