+++ /dev/null
-==========================
- Introduction to librados
-==========================
-
-The :term:`Ceph Storage Cluster` provides the basic storage service that allows
-:term:`Ceph` to uniquely deliver **object, block, and file storage** in one
-unified system. However, you are not limited to using the RESTful, block, or
-POSIX interfaces. Based upon :abbr:`RADOS (Reliable Autonomic Distributed Object
-Store)`, the ``librados`` API enables you to create your own interface to the
-Ceph Storage Cluster.
-
-The ``librados`` API enables you to interact with the two types of daemons in
-the Ceph Storage Cluster:
-
-- The :term:`Ceph Monitor`, which maintains a master copy of the cluster map.
-- The :term:`Ceph OSD Daemon` (OSD), which stores data as objects on a storage node.
-
-.. ditaa::
- +---------------------------------+
- | Ceph Storage Cluster Protocol |
- | (librados) |
- +---------------------------------+
- +---------------+ +---------------+
- | OSDs | | Monitors |
- +---------------+ +---------------+
-
-This guide provides a high-level introduction to using ``librados``.
-Refer to :doc:`../../architecture` for additional details of the Ceph
-Storage Cluster. To use the API, you need a running Ceph Storage Cluster.
-See `Installation (Quick)`_ for details.
-
-
-Step 1: Getting librados
-========================
-
-Your client application must bind with ``librados`` to connect to the Ceph
-Storage Cluster. You must install ``librados`` and any required packages to
-write applications that use ``librados``. The ``librados`` API is written in
-C++, with additional bindings for C, Python, Java and PHP.
-
-
-Getting librados for C/C++
---------------------------
-
-To install ``librados`` development support files for C/C++ on Debian/Ubuntu
-distributions, execute the following::
-
- sudo apt-get install librados-dev
-
-To install ``librados`` development support files for C/C++ on RHEL/CentOS
-distributions, execute the following::
-
- sudo yum install librados2-devel
-
-Once you install ``librados`` for developers, you can find the required
-headers for C/C++ under ``/usr/include/rados``. ::
-
- ls /usr/include/rados
-
-
-Getting librados for Python
----------------------------
-
-The ``rados`` module provides ``librados`` support to Python
-applications. The ``librados-dev`` package for Debian/Ubuntu
-and the ``librados2-devel`` package for RHEL/CentOS will install the
-``python-rados`` package for you. You may install ``python-rados``
-directly too.
-
-To install ``librados`` development support files for Python on Debian/Ubuntu
-distributions, execute the following::
-
- sudo apt-get install python-rados
-
-To install ``librados`` development support files for Python on RHEL/CentOS
-distributions, execute the following::
-
- sudo yum install python-rados
-
-You can find the module under ``/usr/share/pyshared`` on Debian systems,
-or under ``/usr/lib/python*/site-packages`` on CentOS/RHEL systems.
-
-
-Getting librados for Java
--------------------------
-
-To install ``librados`` for Java, you need to execute the following procedure:
-
-#. Install ``jna.jar``. For Debian/Ubuntu, execute::
-
- sudo apt-get install libjna-java
-
- For CentOS/RHEL, execute::
-
- sudo yum install jna
-
- The JAR files are located in ``/usr/share/java``.
-
-#. Clone the ``rados-java`` repository::
-
- git clone --recursive https://github.com/ceph/rados-java.git
-
-#. Build the ``rados-java`` repository::
-
- cd rados-java
- ant
-
- The JAR file is located under ``rados-java/target``.
-
-#. Copy the JAR for RADOS to a common location (e.g., ``/usr/share/java``) and
- ensure that it and the JNA JAR are in your JVM's classpath. For example::
-
- sudo cp target/rados-0.1.3.jar /usr/share/java/rados-0.1.3.jar
- sudo ln -s /usr/share/java/jna-3.2.7.jar /usr/lib/jvm/default-java/jre/lib/ext/jna-3.2.7.jar
- sudo ln -s /usr/share/java/rados-0.1.3.jar /usr/lib/jvm/default-java/jre/lib/ext/rados-0.1.3.jar
-
-To build the documentation, execute the following::
-
- ant docs
-
-
-Getting librados for PHP
--------------------------
-
-To install the ``librados`` extension for PHP, you need to execute the following procedure:
-
-#. Install php-dev. For Debian/Ubuntu, execute::
-
- sudo apt-get install php5-dev build-essential
-
- For CentOS/RHEL, execute::
-
- sudo yum install php-devel
-
-#. Clone the ``phprados`` repository::
-
- git clone https://github.com/ceph/phprados.git
-
-#. Build ``phprados``::
-
- cd phprados
- phpize
- ./configure
- make
- sudo make install
-
-#. Enable ``phprados`` in php.ini by adding::
-
- extension=rados.so
-
-
-Step 2: Configuring a Cluster Handle
-====================================
-
-A :term:`Ceph Client`, via ``librados``, interacts directly with OSDs to store
-and retrieve data. To interact with OSDs, the client app must invoke
-``librados`` and connect to a Ceph Monitor. Once connected, ``librados``
-retrieves the :term:`Cluster Map` from the Ceph Monitor. When the client app
-wants to read or write data, it creates an I/O context and binds to a
-:term:`pool`. The pool has an associated :term:`ruleset` that defines how it
-will place data in the storage cluster. Via the I/O context, the client
-provides the object name to ``librados``, which takes the object name
-and the cluster map (i.e., the topology of the cluster) and `computes`_ the
-placement group and `OSD`_ for locating the data. Then the client application
-can read or write data. The client app doesn't need to learn about the topology
-of the cluster directly.
-
-.. ditaa::
- +--------+ Retrieves +---------------+
- | Client |------------>| Cluster Map |
- +--------+ +---------------+
- |
- v Writes
- /-----\
- | obj |
- \-----/
- | To
- v
- +--------+ +---------------+
- | Pool |---------->| CRUSH Ruleset |
- +--------+ Selects +---------------+
-
-
-The Ceph Storage Cluster handle encapsulates the client configuration, including:
-
-- The `user ID`_ for ``rados_create()`` or user name for ``rados_create2()``
- (preferred).
-- The :term:`cephx` authentication key
-- The monitor ID and IP address
-- Logging levels
-- Debugging levels
-
-Thus, the first steps in using the cluster from your app are to 1) create
-a cluster handle that your app will use to connect to the storage cluster,
-and then 2) use that handle to connect. To connect to the cluster, the
-app must supply a monitor address, a username and an authentication key
-(cephx is enabled by default).
-
-.. tip:: Talking to different Ceph Storage Clusters – or to the same cluster
- with different users – requires different cluster handles.
-
-RADOS provides a number of ways for you to set the required values. For
-the monitor and encryption key settings, an easy way to handle them is to ensure
-that your Ceph configuration file contains a ``keyring`` path to a keyring file
-and at least one monitor address (e.g,. ``mon host``). For example::
-
- [global]
- mon host = 192.168.1.1
- keyring = /etc/ceph/ceph.client.admin.keyring
-
-Once you create the handle, you can read a Ceph configuration file to configure
-the handle. You can also pass arguments to your app and parse them with the
-function for parsing command line arguments (e.g., ``rados_conf_parse_argv()``),
-or parse Ceph environment variables (e.g., ``rados_conf_parse_env()``). Some
-wrappers may not implement convenience methods, so you may need to implement
-these capabilities. The following diagram provides a high-level flow for the
-initial connection.
-
-
-.. ditaa:: +---------+ +---------+
- | Client | | Monitor |
- +---------+ +---------+
- | |
- |-----+ create |
- | | cluster |
- |<----+ handle |
- | |
- |-----+ read |
- | | config |
- |<----+ file |
- | |
- | connect |
- |-------------->|
- | |
- |<--------------|
- | connected |
- | |
-
-
-Once connected, your app can invoke functions that affect the whole cluster
-with only the cluster handle. For example, once you have a cluster
-handle, you can:
-
-- Get cluster statistics
-- Use Pool Operation (exists, create, list, delete)
-- Get and set the configuration
-
-
-One of the powerful features of Ceph is the ability to bind to different pools.
-Each pool may have a different number of placement groups, object replicas and
-replication strategies. For example, a pool could be set up as a "hot" pool that
-uses SSDs for frequently used objects or a "cold" pool that uses erasure coding.
-
-The main difference in the various ``librados`` bindings is between C and
-the object-oriented bindings for C++, Java and Python. The object-oriented
-bindings use objects to represent cluster handles, IO Contexts, iterators,
-exceptions, etc.
-
-
-C Example
----------
-
-For C, creating a simple cluster handle using the ``admin`` user, configuring
-it and connecting to the cluster might look something like this:
-
-.. code-block:: c
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <rados/librados.h>
-
- int main (int argc, const char **argv)
- {
-
- /* Declare the cluster handle and required arguments. */
- rados_t cluster;
- char cluster_name[] = "ceph";
- char user_name[] = "client.admin";
- uint64_t flags;
-
- /* Initialize the cluster handle with the "ceph" cluster name and the "client.admin" user */
- int err;
- err = rados_create2(&cluster, cluster_name, user_name, flags);
-
- if (err < 0) {
- fprintf(stderr, "%s: Couldn't create the cluster handle! %s\n", argv[0], strerror(-err));
- exit(EXIT_FAILURE);
- } else {
- printf("\nCreated a cluster handle.\n");
- }
-
-
- /* Read a Ceph configuration file to configure the cluster handle. */
- err = rados_conf_read_file(cluster, "/etc/ceph/ceph.conf");
- if (err < 0) {
- fprintf(stderr, "%s: cannot read config file: %s\n", argv[0], strerror(-err));
- exit(EXIT_FAILURE);
- } else {
- printf("\nRead the config file.\n");
- }
-
- /* Read command line arguments */
- err = rados_conf_parse_argv(cluster, argc, argv);
- if (err < 0) {
- fprintf(stderr, "%s: cannot parse command line arguments: %s\n", argv[0], strerror(-err));
- exit(EXIT_FAILURE);
- } else {
- printf("\nRead the command line arguments.\n");
- }
-
- /* Connect to the cluster */
- err = rados_connect(cluster);
- if (err < 0) {
- fprintf(stderr, "%s: cannot connect to cluster: %s\n", argv[0], strerror(-err));
- exit(EXIT_FAILURE);
- } else {
- printf("\nConnected to the cluster.\n");
- }
-
- }
-
-Compile your client and link to ``librados`` using ``-lrados``. For example::
-
- gcc ceph-client.c -lrados -o ceph-client
-
-
-C++ Example
------------
-
-The Ceph project provides a C++ example in the ``ceph/examples/librados``
-directory. For C++, a simple cluster handle using the ``admin`` user requires
-you to initialize a ``librados::Rados`` cluster handle object:
-
-.. code-block:: c++
-
- #include <iostream>
- #include <string>
- #include <rados/librados.hpp>
-
- int main(int argc, const char **argv)
- {
-
- int ret = 0;
-
- /* Declare the cluster handle and required variables. */
- librados::Rados cluster;
- char cluster_name[] = "ceph";
- char user_name[] = "client.admin";
- uint64_t flags = 0;
-
- /* Initialize the cluster handle with the "ceph" cluster name and "client.admin" user */
- {
- ret = cluster.init2(user_name, cluster_name, flags);
- if (ret < 0) {
- std::cerr << "Couldn't initialize the cluster handle! error " << ret << std::endl;
- return EXIT_FAILURE;
- } else {
- std::cout << "Created a cluster handle." << std::endl;
- }
- }
-
- /* Read a Ceph configuration file to configure the cluster handle. */
- {
- ret = cluster.conf_read_file("/etc/ceph/ceph.conf");
- if (ret < 0) {
- std::cerr << "Couldn't read the Ceph configuration file! error " << ret << std::endl;
- return EXIT_FAILURE;
- } else {
- std::cout << "Read the Ceph configuration file." << std::endl;
- }
- }
-
- /* Read command line arguments */
- {
- ret = cluster.conf_parse_argv(argc, argv);
- if (ret < 0) {
- std::cerr << "Couldn't parse command line options! error " << ret << std::endl;
- return EXIT_FAILURE;
- } else {
- std::cout << "Parsed command line options." << std::endl;
- }
- }
-
- /* Connect to the cluster */
- {
- ret = cluster.connect();
- if (ret < 0) {
- std::cerr << "Couldn't connect to cluster! error " << ret << std::endl;
- return EXIT_FAILURE;
- } else {
- std::cout << "Connected to the cluster." << std::endl;
- }
- }
-
- return 0;
- }
-
-
-Compile the source; then, link ``librados`` using ``-lrados``.
-For example::
-
- g++ -g -c ceph-client.cc -o ceph-client.o
- g++ -g ceph-client.o -lrados -o ceph-client
-
-
-
-Python Example
---------------
-
-Python uses the ``admin`` id and the ``ceph`` cluster name by default, and
-will read the standard ``ceph.conf`` file if the conffile parameter is
-set to the empty string. The Python binding converts C++ errors
-into exceptions.
-
-
-.. code-block:: python
-
- import rados
-
- try:
- cluster = rados.Rados(conffile='')
- except TypeError as e:
- print 'Argument validation error: ', e
- raise e
-
- print "Created cluster handle."
-
- try:
- cluster.connect()
- except Exception as e:
- print "connection error: ", e
- raise e
- finally:
- print "Connected to the cluster."
-
-
-Execute the example to verify that it connects to your cluster. ::
-
- python ceph-client.py
-
-
-Java Example
-------------
-
-Java requires you to specify the user ID (``admin``) or user name
-(``client.admin``), and uses the ``ceph`` cluster name by default . The Java
-binding converts C++-based errors into exceptions.
-
-.. code-block:: java
-
- import com.ceph.rados.Rados;
- import com.ceph.rados.RadosException;
-
- import java.io.File;
-
- public class CephClient {
- public static void main (String args[]){
-
- try {
- Rados cluster = new Rados("admin");
- System.out.println("Created cluster handle.");
-
- File f = new File("/etc/ceph/ceph.conf");
- cluster.confReadFile(f);
- System.out.println("Read the configuration file.");
-
- cluster.connect();
- System.out.println("Connected to the cluster.");
-
- } catch (RadosException e) {
- System.out.println(e.getMessage() + ": " + e.getReturnValue());
- }
- }
- }
-
-
-Compile the source; then, run it. If you have copied the JAR to
-``/usr/share/java`` and sym linked from your ``ext`` directory, you won't need
-to specify the classpath. For example::
-
- javac CephClient.java
- java CephClient
-
-
-PHP Example
-------------
-
-With the RADOS extension enabled in PHP you can start creating a new cluster handle very easily:
-
-.. code-block:: php
-
- <?php
-
- $r = rados_create();
- rados_conf_read_file($r, '/etc/ceph/ceph.conf');
- if (!rados_connect($r)) {
- echo "Failed to connect to Ceph cluster";
- } else {
- echo "Successfully connected to Ceph cluster";
- }
-
-
-Save this as rados.php and run the code::
-
- php rados.php
-
-
-Step 3: Creating an I/O Context
-===============================
-
-Once your app has a cluster handle and a connection to a Ceph Storage Cluster,
-you may create an I/O Context and begin reading and writing data. An I/O Context
-binds the connection to a specific pool. The user must have appropriate
-`CAPS`_ permissions to access the specified pool. For example, a user with read
-access but not write access will only be able to read data. I/O Context
-functionality includes:
-
-- Write/read data and extended attributes
-- List and iterate over objects and extended attributes
-- Snapshot pools, list snapshots, etc.
-
-
-.. ditaa:: +---------+ +---------+ +---------+
- | Client | | Monitor | | OSD |
- +---------+ +---------+ +---------+
- | | |
- |-----+ create | |
- | | I/O | |
- |<----+ context | |
- | | |
- | write data | |
- |---------------+-------------->|
- | | |
- | write ack | |
- |<--------------+---------------|
- | | |
- | write xattr | |
- |---------------+-------------->|
- | | |
- | xattr ack | |
- |<--------------+---------------|
- | | |
- | read data | |
- |---------------+-------------->|
- | | |
- | read ack | |
- |<--------------+---------------|
- | | |
- | remove data | |
- |---------------+-------------->|
- | | |
- | remove ack | |
- |<--------------+---------------|
-
-
-
-RADOS enables you to interact both synchronously and asynchronously. Once your
-app has an I/O Context, read/write operations only require you to know the
-object/xattr name. The CRUSH algorithm encapsulated in ``librados`` uses the
-cluster map to identify the appropriate OSD. OSD daemons handle the replication,
-as described in `Smart Daemons Enable Hyperscale`_. The ``librados`` library also
-maps objects to placement groups, as described in `Calculating PG IDs`_.
-
-The following examples use the default ``data`` pool. However, you may also
-use the API to list pools, ensure they exist, or create and delete pools. For
-the write operations, the examples illustrate how to use synchronous mode. For
-the read operations, the examples illustrate how to use asynchronous mode.
-
-.. important:: Use caution when deleting pools with this API. If you delete
- a pool, the pool and ALL DATA in the pool will be lost.
-
-
-C Example
----------
-
-
-.. code-block:: c
-
- #include <stdio.h>
- #include <stdlib.h>
- #include <string.h>
- #include <rados/librados.h>
-
- int main (int argc, const char **argv)
- {
- /*
- * Continued from previous C example, where cluster handle and
- * connection are established. First declare an I/O Context.
- */
-
- rados_ioctx_t io;
- char *poolname = "data";
-
- 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(EXIT_FAILURE);
- } else {
- printf("\nCreated I/O context.\n");
- }
-
- /* Write data to the cluster synchronously. */
- err = rados_write(io, "hw", "Hello World!", 12, 0);
- if (err < 0) {
- fprintf(stderr, "%s: Cannot write object \"hw\" to pool %s: %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nWrote \"Hello World\" to object \"hw\".\n");
- }
-
- char xattr[] = "en_US";
- err = rados_setxattr(io, "hw", "lang", xattr, 5);
- if (err < 0) {
- fprintf(stderr, "%s: Cannot write xattr to pool %s: %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nWrote \"en_US\" to xattr \"lang\" for object \"hw\".\n");
- }
-
- /*
- * Read data from the cluster asynchronously.
- * First, set up asynchronous I/O completion.
- */
- 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);
- } else {
- printf("\nCreated AIO completion.\n");
- }
-
- /* Next, read data using rados_aio_read. */
- char read_res[100];
- err = rados_aio_read(io, "hw", comp, read_res, 12, 0);
- if (err < 0) {
- fprintf(stderr, "%s: Cannot read object. %s %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nRead object \"hw\". The contents are:\n %s \n", read_res);
- }
-
- /* Wait for the operation to complete */
- rados_aio_wait_for_complete(comp);
-
- /* Release the asynchronous I/O complete handle to avoid memory leaks. */
- rados_aio_release(comp);
-
-
- char xattr_res[100];
- err = rados_getxattr(io, "hw", "lang", xattr_res, 5);
- if (err < 0) {
- fprintf(stderr, "%s: Cannot read xattr. %s %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nRead xattr \"lang\" for object \"hw\". The contents are:\n %s \n", xattr_res);
- }
-
- err = rados_rmxattr(io, "hw", "lang");
- if (err < 0) {
- fprintf(stderr, "%s: Cannot remove xattr. %s %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nRemoved xattr \"lang\" for object \"hw\".\n");
- }
-
- err = rados_remove(io, "hw");
- if (err < 0) {
- fprintf(stderr, "%s: Cannot remove object. %s %s\n", argv[0], poolname, strerror(-err));
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
- exit(1);
- } else {
- printf("\nRemoved object \"hw\".\n");
- }
-
- }
-
-
-
-C++ Example
------------
-
-
-.. code-block:: c++
-
- #include <iostream>
- #include <string>
- #include <rados/librados.hpp>
-
- int main(int argc, const char **argv)
- {
-
- /* Continued from previous C++ example, where cluster handle and
- * connection are established. First declare an I/O Context.
- */
-
- librados::IoCtx io_ctx;
- const char *pool_name = "data";
-
- {
- ret = cluster.ioctx_create(pool_name, io_ctx);
- if (ret < 0) {
- std::cerr << "Couldn't set up ioctx! error " << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Created an ioctx for the pool." << std::endl;
- }
- }
-
-
- /* Write an object synchronously. */
- {
- librados::bufferlist bl;
- bl.append("Hello World!");
- ret = io_ctx.write_full("hw", bl);
- if (ret < 0) {
- std::cerr << "Couldn't write object! error " << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Wrote new object 'hw' " << std::endl;
- }
- }
-
-
- /*
- * Add an xattr to the object.
- */
- {
- librados::bufferlist lang_bl;
- lang_bl.append("en_US");
- ret = io_ctx.setxattr("hw", "lang", lang_bl);
- if (ret < 0) {
- std::cerr << "failed to set xattr version entry! error "
- << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Set the xattr 'lang' on our object!" << std::endl;
- }
- }
-
-
- /*
- * Read the object back asynchronously.
- */
- {
- librados::bufferlist read_buf;
- int read_len = 4194304;
-
- //Create I/O Completion.
- librados::AioCompletion *read_completion = librados::Rados::aio_create_completion();
-
- //Send read request.
- ret = io_ctx.aio_read("hw", read_completion, &read_buf, read_len, 0);
- if (ret < 0) {
- std::cerr << "Couldn't start read object! error " << ret << std::endl;
- exit(EXIT_FAILURE);
- }
-
- // Wait for the request to complete, and check that it succeeded.
- read_completion->wait_for_complete();
- ret = read_completion->get_return_value();
- if (ret < 0) {
- std::cerr << "Couldn't read object! error " << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Read object hw asynchronously with contents.\n"
- << read_buf.c_str() << std::endl;
- }
- }
-
-
- /*
- * Read the xattr.
- */
- {
- librados::bufferlist lang_res;
- ret = io_ctx.getxattr("hw", "lang", lang_res);
- if (ret < 0) {
- std::cerr << "failed to get xattr version entry! error "
- << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Got the xattr 'lang' from object hw!"
- << lang_res.c_str() << std::endl;
- }
- }
-
-
- /*
- * Remove the xattr.
- */
- {
- ret = io_ctx.rmxattr("hw", "lang");
- if (ret < 0) {
- std::cerr << "Failed to remove xattr! error "
- << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Removed the xattr 'lang' from our object!" << std::endl;
- }
- }
-
- /*
- * Remove the object.
- */
- {
- ret = io_ctx.remove("hw");
- if (ret < 0) {
- std::cerr << "Couldn't remove object! error " << ret << std::endl;
- exit(EXIT_FAILURE);
- } else {
- std::cout << "Removed object 'hw'." << std::endl;
- }
- }
- }
-
-
-
-Python Example
---------------
-
-.. code-block:: python
-
- print "\n\nI/O Context and Object Operations"
- print "================================="
-
- print "\nCreating a context for the 'data' pool"
- if not cluster.pool_exists('data'):
- raise RuntimeError('No data pool exists')
- ioctx = cluster.open_ioctx('data')
-
- print "\nWriting object 'hw' with contents 'Hello World!' to pool 'data'."
- ioctx.write("hw", "Hello World!")
- print "Writing XATTR 'lang' with value 'en_US' to object 'hw'"
- ioctx.set_xattr("hw", "lang", "en_US")
-
-
- print "\nWriting object 'bm' with contents 'Bonjour tout le monde!' to pool 'data'."
- ioctx.write("bm", "Bonjour tout le monde!")
- print "Writing XATTR 'lang' with value 'fr_FR' to object 'bm'"
- ioctx.set_xattr("bm", "lang", "fr_FR")
-
- print "\nContents of object 'hw'\n------------------------"
- print ioctx.read("hw")
-
- print "\n\nGetting XATTR 'lang' from object 'hw'"
- print ioctx.get_xattr("hw", "lang")
-
- print "\nContents of object 'bm'\n------------------------"
- print ioctx.read("bm")
-
- print "Getting XATTR 'lang' from object 'bm'"
- print ioctx.get_xattr("bm", "lang")
-
-
- print "\nRemoving object 'hw'"
- ioctx.remove_object("hw")
-
- print "Removing object 'bm'"
- ioctx.remove_object("bm")
-
-
-Java-Example
-------------
-
-.. code-block:: java
-
- import com.ceph.rados.Rados;
- import com.ceph.rados.RadosException;
-
- import java.io.File;
- import com.ceph.rados.IoCTX;
-
- public class CephClient {
- public static void main (String args[]){
-
- try {
- Rados cluster = new Rados("admin");
- System.out.println("Created cluster handle.");
-
- File f = new File("/etc/ceph/ceph.conf");
- cluster.confReadFile(f);
- System.out.println("Read the configuration file.");
-
- cluster.connect();
- System.out.println("Connected to the cluster.");
-
- IoCTX io = cluster.ioCtxCreate("data");
-
- String oidone = "hw";
- String contentone = "Hello World!";
- io.write(oidone, contentone);
-
- String oidtwo = "bm";
- String contenttwo = "Bonjour tout le monde!";
- io.write(oidtwo, contenttwo);
-
- String[] objects = io.listObjects();
- for (String object: objects)
- System.out.println(object);
-
- io.remove(oidone);
- io.remove(oidtwo);
-
- cluster.ioCtxDestroy(io);
-
- } catch (RadosException e) {
- System.out.println(e.getMessage() + ": " + e.getReturnValue());
- }
- }
- }
-
-
-PHP Example
------------
-
-.. code-block:: php
-
- <?php
-
- $io = rados_ioctx_create($r, "mypool");
- rados_write_full($io, "oidOne", "mycontents");
- rados_remove("oidOne");
- rados_ioctx_destroy($io);
-
-
-Step 4: Closing Sessions
-========================
-
-Once your app finishes with the I/O Context and cluster handle, the app should
-close the connection and shutdown the handle. For asynchronous I/O, the app
-should also ensure that pending asynchronous operations have completed.
-
-
-C Example
----------
-
-.. code-block:: c
-
- rados_ioctx_destroy(io);
- rados_shutdown(cluster);
-
-
-C++ Example
------------
-
-.. code-block:: c++
-
- io_ctx.close();
- cluster.shutdown();
-
-
-Java Example
---------------
-
-.. code-block:: java
-
- cluster.ioCtxDestroy(io);
- cluster.shutDown();
-
-
-Python Example
---------------
-
-.. code-block:: python
-
- print "\nClosing the connection."
- ioctx.close()
-
- print "Shutting down the handle."
- cluster.shutdown()
-
-PHP Example
------------
-
-.. code-block:: php
-
- rados_shutdown($r);
-
-
-
-.. _user ID: ../../operations/user-management#command-line-usage
-.. _CAPS: ../../operations/user-management#authorization-capabilities
-.. _Installation (Quick): ../../../start
-.. _Smart Daemons Enable Hyperscale: ../../../architecture#smart-daemons-enable-hyperscale
-.. _Calculating PG IDs: ../../../architecture#calculating-pg-ids
-.. _computes: ../../../architecture#calculating-pg-ids
-.. _OSD: ../../../architecture#mapping-pgs-to-osds
Code Review / stor4nfv.git / blobdiff