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>

1 files changed, 187 insertions, 0 deletions

diff --git a/src/ceph/doc/rados/api/librados.rst b/src/ceph/doc/rados/api/librados.rst
new file mode 100644
index 0000000..73d0e42
--- /dev/null
+++ b/src/ceph/doc/rados/api/librados.rst
@@ -0,0 +1,187 @@
+==============
+ Librados (C)
+==============
+
+.. highlight:: c
+
+`librados` provides low-level access to the RADOS service. For an
+overview of RADOS, see :doc:`../../architecture`.
+
+
+Example: connecting and writing an object
+=========================================
+
+To use `Librados`, you instantiate a :c:type:`rados_t` variable (a cluster handle) and
+call :c:func:`rados_create()` with a pointer to it::
+
+	int err;
+	rados_t cluster;
+
+	err = rados_create(&cluster, NULL);
+	if (err < 0) {
+		fprintf(stderr, "%s: cannot create a cluster handle: %s\n", argv[0], strerror(-err));
+		exit(1);
+	}
+
+Then you configure your :c:type:`rados_t` to connect to your cluster,
+either by setting individual values (:c:func:`rados_conf_set()`),
+using a configuration file (:c:func:`rados_conf_read_file()`), using
+command line options (:c:func:`rados_conf_parse_argv`), or an
+environment variable (:c:func:`rados_conf_parse_env()`)::
+
+	err = rados_conf_read_file(cluster, "/path/to/myceph.conf");
+	if (err < 0) {
+		fprintf(stderr, "%s: cannot read config file: %s\n", argv[0], strerror(-err));
+		exit(1);
+	}
+
+Once the cluster handle is configured, you can connect to the cluster with :c:func:`rados_connect()`::
+
+	err = rados_connect(cluster);
+	if (err < 0) {
+		fprintf(stderr, "%s: cannot connect to cluster: %s\n", argv[0], strerror(-err));
+		exit(1);
+	}
+
+Then you open an "IO context", a :c:type:`rados_ioctx_t`, with :c:func:`rados_ioctx_create()`::
+
+	rados_ioctx_t io;
+	char *poolname = "mypool";
+
+	err = rados_ioctx_create(cluster, poolname, &io);
+	if (err < 0) {
+		fprintf(stderr, "%s: cannot open rados pool %s: %s\n", argv[0], poolname, strerror(-err));
+		rados_shutdown(cluster);
+		exit(1);
+	}
+
+Note that the pool you try to access must exist.
+
+Then you can use the RADOS data manipulation functions, for example
+write into an object called ``greeting`` with
+:c:func:`rados_write_full()`::
+
+	err = rados_write_full(io, "greeting", "hello", 5);
+	if (err < 0) {
+		fprintf(stderr, "%s: cannot write pool %s: %s\n", argv[0], poolname, strerror(-err));
+		rados_ioctx_destroy(io);
+		rados_shutdown(cluster);
+		exit(1);
+	}
+
+In the end, you will want to close your IO context and connection to RADOS with :c:func:`rados_ioctx_destroy()` and :c:func:`rados_shutdown()`::
+
+	rados_ioctx_destroy(io);
+	rados_shutdown(cluster);
+
+
+Asychronous IO
+==============
+
+When doing lots of IO, you often don't need to wait for one operation
+to complete before starting the next one. `Librados` provides
+asynchronous versions of several operations:
+
+* :c:func:`rados_aio_write`
+* :c:func:`rados_aio_append`
+* :c:func:`rados_aio_write_full`
+* :c:func:`rados_aio_read`
+
+For each operation, you must first create a
+:c:type:`rados_completion_t` that represents what to do when the
+operation is safe or complete by calling
+:c:func:`rados_aio_create_completion`. If you don't need anything
+special to happen, you can pass NULL::
+
+	rados_completion_t comp;
+	err = rados_aio_create_completion(NULL, NULL, NULL, &comp);
+	if (err < 0) {
+		fprintf(stderr, "%s: could not create aio completion: %s\n", argv[0], strerror(-err));
+		rados_ioctx_destroy(io);
+		rados_shutdown(cluster);
+		exit(1);
+	}
+
+Now you can call any of the aio operations, and wait for it to
+be in memory or on disk on all replicas::
+
+	err = rados_aio_write(io, "foo", comp, "bar", 3, 0);
+	if (err < 0) {
+		fprintf(stderr, "%s: could not schedule aio write: %s\n", argv[0], strerror(-err));
+		rados_aio_release(comp);
+		rados_ioctx_destroy(io);
+		rados_shutdown(cluster);
+		exit(1);
+	}
+	rados_aio_wait_for_complete(comp); // in memory
+	rados_aio_wait_for_safe(comp); // on disk
+
+Finally, we need to free the memory used by the completion with :c:func:`rados_aio_release`::
+
+	rados_aio_release(comp);
+
+You can use the callbacks to tell your application when writes are
+durable, or when read buffers are full. For example, if you wanted to
+measure the latency of each operation when appending to several
+objects, you could schedule several writes and store the ack and
+commit time in the corresponding callback, then wait for all of them
+to complete using :c:func:`rados_aio_flush` before analyzing the
+latencies::
+
+	typedef struct {
+		struct timeval start;
+		struct timeval ack_end;
+		struct timeval commit_end;
+	} req_duration;
+
+	void ack_callback(rados_completion_t comp, void *arg) {
+		req_duration *dur = (req_duration *) arg;
+		gettimeofday(&dur->ack_end, NULL);
+	}
+
+	void commit_callback(rados_completion_t comp, void *arg) {
+		req_duration *dur = (req_duration *) arg;
+		gettimeofday(&dur->commit_end, NULL);
+	}
+
+	int output_append_latency(rados_ioctx_t io, const char *data, size_t len, size_t num_writes) {
+		req_duration times[num_writes];
+		rados_completion_t comps[num_writes];
+		for (size_t i = 0; i < num_writes; ++i) {
+			gettimeofday(&times[i].start, NULL);
+			int err = rados_aio_create_completion((void*) &times[i], ack_callback, commit_callback, &comps[i]);
+			if (err < 0) {
+				fprintf(stderr, "Error creating rados completion: %s\n", strerror(-err));
+				return err;
+			}
+			char obj_name[100];
+			snprintf(obj_name, sizeof(obj_name), "foo%ld", (unsigned long)i);
+			err = rados_aio_append(io, obj_name, comps[i], data, len);
+			if (err < 0) {
+				fprintf(stderr, "Error from rados_aio_append: %s", strerror(-err));
+				return err;
+			}
+		}
+		// wait until all requests finish *and* the callbacks complete
+		rados_aio_flush(io);
+		// the latencies can now be analyzed
+		printf("Request # | Ack latency (s) | Commit latency (s)\n");
+		for (size_t i = 0; i < num_writes; ++i) {
+			// don't forget to free the completions
+			rados_aio_release(comps[i]);
+			struct timeval ack_lat, commit_lat;
+			timersub(&times[i].ack_end, &times[i].start, &ack_lat);
+			timersub(&times[i].commit_end, &times[i].start, &commit_lat);
+			printf("%9ld | %8ld.%06ld | %10ld.%06ld\n", (unsigned long) i, ack_lat.tv_sec, ack_lat.tv_usec, commit_lat.tv_sec, commit_lat.tv_usec);
+		}
+		return 0;
+	}
+
+Note that all the :c:type:`rados_completion_t` must be freed with :c:func:`rados_aio_release` to avoid leaking memory.
+
+
+API calls
+=========
+
+ .. autodoxygenfile:: rados_types.h
+ .. autodoxygenfile:: librados.h