+++ /dev/null
-// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
-// vim: ts=8 sw=2 smarttab
-
-/*
- * This is a simple example RADOS class, designed to be usable as a
- * template for implementing new methods.
- *
- * Our goal here is to illustrate the interface between the OSD and
- * the class and demonstrate what kinds of things a class can do.
- *
- * Note that any *real* class will probably have a much more
- * sophisticated protocol dealing with the in and out data buffers.
- * For an example of the model that we've settled on for handling that
- * in a clean way, please refer to cls_lock or cls_version for
- * relatively simple examples of how the parameter encoding can be
- * encoded in a way that allows for forward and backward compatibility
- * between client vs class revisions.
- */
-
-/*
- * A quick note about bufferlists:
- *
- * The bufferlist class allows memory buffers to be concatenated,
- * truncated, spliced, "copied," encoded/embedded, and decoded. For
- * most operations no actual data is ever copied, making bufferlists
- * very convenient for efficiently passing data around.
- *
- * bufferlist is actually a typedef of buffer::list, and is defined in
- * include/buffer.h (and implemented in common/buffer.cc).
- */
-
-#include <algorithm>
-#include <string>
-#include <sstream>
-#include <errno.h>
-
-#include "objclass/objclass.h"
-
-CLS_VER(1,0)
-CLS_NAME(hello)
-
-/**
- * say hello - a "read" method that does not depend on the object
- *
- * This is an example of a method that does some computation and
- * returns data to the caller, without depending on the local object
- * content.
- */
-static int say_hello(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- // see if the input data from the client matches what this method
- // expects to receive. your class can fill this buffer with what it
- // wants.
- if (in->length() > 100)
- return -EINVAL;
-
- // we generate our reply
- out->append("Hello, ");
- if (in->length() == 0)
- out->append("world");
- else
- out->append(*in);
- out->append("!");
-
- // this return value will be returned back to the librados caller
- return 0;
-}
-
-/**
- * record hello - a "write" method that creates an object
- *
- * This method modifies a local object (in this case, by creating it
- * if it doesn't exist). We make multiple write calls (write,
- * setxattr) which are accumulated and applied as an atomic
- * transaction.
- */
-static int record_hello(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- // we can write arbitrary stuff to the ceph-osd debug log. each log
- // message is accompanied by an integer log level. smaller is
- // "louder". how much of this makes it into the log is controlled
- // by the debug_cls option on the ceph-osd, similar to how other log
- // levels are controlled. this message, at level 20, will generally
- // not be seen by anyone unless debug_cls is set at 20 or higher.
- CLS_LOG(20, "in record_hello");
-
- // see if the input data from the client matches what this method
- // expects to receive. your class can fill this buffer with what it
- // wants.
- if (in->length() > 100)
- return -EINVAL;
-
- // only say hello to non-existent objects
- if (cls_cxx_stat(hctx, NULL, NULL) == 0)
- return -EEXIST;
-
- bufferlist content;
- content.append("Hello, ");
- if (in->length() == 0)
- content.append("world");
- else
- content.append(*in);
- content.append("!");
-
- // create/write the object
- int r = cls_cxx_write_full(hctx, &content);
- if (r < 0)
- return r;
-
- // also make note of who said it
- entity_inst_t origin;
- cls_get_request_origin(hctx, &origin);
- ostringstream ss;
- ss << origin;
- bufferlist attrbl;
- attrbl.append(ss.str());
- r = cls_cxx_setxattr(hctx, "said_by", &attrbl);
- if (r < 0)
- return r;
-
- // For write operations, there are two possible outcomes:
- //
- // * For a failure, we return a negative error code. The out
- // buffer can contain any data that we want, and that data will
- // be returned to the caller. No change is made to the object.
- //
- // * For a success, we must return 0 and *no* data in the out
- // buffer. This is becaues the OSD does not log write result
- // codes or output buffers and we need a replayed/resent
- // operation (e.g., after a TCP disconnect) to be idempotent.
- //
- // If a class returns a positive value or puts data in the out
- // buffer, the OSD code will ignore it and return 0 to the
- // client.
- return 0;
-}
-
-static int writes_dont_return_data(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- // make some change to the object
- bufferlist attrbl;
- attrbl.append("bar");
- int r = cls_cxx_setxattr(hctx, "foo", &attrbl);
- if (r < 0)
- return r;
-
- if (in->length() > 0) {
- // note that if we return anything < 0 (an error), this
- // operation/transaction will abort, and the setattr above will
- // never happen. however, we *can* return data on error.
- out->append("too much input data!");
- return -EINVAL;
- }
-
- // try to return some data. note that this *won't* reach the
- // client! see the matching test case in test_cls_hello.cc.
- out->append("you will never see this");
-
- // if we try to return anything > 0 here the client will see 0.
- return 42;
-}
-
-
-/**
- * replay - a "read" method to get a previously recorded hello
- *
- * This is a read method that will retrieve a previously recorded
- * hello statement.
- */
-static int replay(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- // read contents out of the on-disk object. our behavior can be a
- // function of either the request alone, or the request and the
- // on-disk state, depending on whether the RD flag is specified when
- // registering the method (see the __cls__init function below).
- int r = cls_cxx_read(hctx, 0, 1100, out);
- if (r < 0)
- return r;
-
- // note that our return value need not be the length of the returned
- // data; it can be whatever value we want: positive, zero or
- // negative (this is a read).
- return 0;
-}
-
-/**
- * turn_it_to_11 - a "write" method that mutates existing object data
- *
- * A write method can depend on previous object content (i.e., perform
- * a read/modify/write operation). This atomically transitions the
- * object state from the old content to the new content.
- */
-static int turn_it_to_11(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- // see if the input data from the client matches what this method
- // expects to receive. your class can fill this buffer with what it
- // wants.
- if (in->length() != 0)
- return -EINVAL;
-
- bufferlist previous;
- int r = cls_cxx_read(hctx, 0, 1100, &previous);
- if (r < 0)
- return r;
-
- std::string str(previous.c_str(), previous.length());
- std::transform(str.begin(), str.end(), str.begin(), ::toupper);
- previous.clear();
- previous.append(str);
-
- // replace previous byte data content (write_full == truncate(0) + write)
- r = cls_cxx_write_full(hctx, &previous);
- if (r < 0)
- return r;
-
- // record who did it
- entity_inst_t origin;
- cls_get_request_origin(hctx, &origin);
- ostringstream ss;
- ss << origin;
- bufferlist attrbl;
- attrbl.append(ss.str());
- r = cls_cxx_setxattr(hctx, "amplified_by", &attrbl);
- if (r < 0)
- return r;
-
- // return value is 0 for success; out buffer is empty.
- return 0;
-}
-
-/**
- * example method that does not behave
- *
- * This method is registered as WR but tries to read
- */
-static int bad_reader(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- return cls_cxx_read(hctx, 0, 100, out);
-}
-
-/**
- * example method that does not behave
- *
- * This method is registered as RD but tries to write
- */
-static int bad_writer(cls_method_context_t hctx, bufferlist *in, bufferlist *out)
-{
- return cls_cxx_write_full(hctx, in);
-}
-
-
-class PGLSHelloFilter : public PGLSFilter {
- string val;
-public:
- int init(bufferlist::iterator& params) override {
- try {
- ::decode(xattr, params);
- ::decode(val, params);
- } catch (buffer::error &e) {
- return -EINVAL;
- }
- return 0;
- }
-
- ~PGLSHelloFilter() override {}
- bool filter(const hobject_t &obj, bufferlist& xattr_data,
- bufferlist& outdata) override
- {
- if (val.size() != xattr_data.length())
- return false;
-
- if (memcmp(val.c_str(), xattr_data.c_str(), val.size()))
- return false;
-
- return true;
- }
-};
-
-
-PGLSFilter *hello_filter()
-{
- return new PGLSHelloFilter();
-}
-
-
-/**
- * initialize class
- *
- * We do two things here: we register the new class, and then register
- * all of the class's methods.
- */
-CLS_INIT(hello)
-{
- // this log message, at level 0, will always appear in the ceph-osd
- // log file.
- CLS_LOG(0, "loading cls_hello");
-
- cls_handle_t h_class;
- cls_method_handle_t h_say_hello;
- cls_method_handle_t h_record_hello;
- cls_method_handle_t h_replay;
- cls_method_handle_t h_writes_dont_return_data;
- cls_method_handle_t h_turn_it_to_11;
- cls_method_handle_t h_bad_reader;
- cls_method_handle_t h_bad_writer;
-
- cls_register("hello", &h_class);
-
- // There are two flags we specify for methods:
- //
- // RD : whether this method (may) read prior object state
- // WR : whether this method (may) write or update the object
- //
- // A method can be RD, WR, neither, or both. If a method does
- // neither, the data it returns to the caller is a function of the
- // request and not the object contents.
-
- cls_register_cxx_method(h_class, "say_hello",
- CLS_METHOD_RD,
- say_hello, &h_say_hello);
- cls_register_cxx_method(h_class, "record_hello",
- CLS_METHOD_WR | CLS_METHOD_PROMOTE,
- record_hello, &h_record_hello);
- cls_register_cxx_method(h_class, "writes_dont_return_data",
- CLS_METHOD_WR,
- writes_dont_return_data, &h_writes_dont_return_data);
- cls_register_cxx_method(h_class, "replay",
- CLS_METHOD_RD,
- replay, &h_replay);
-
- // RD | WR is a read-modify-write method.
- cls_register_cxx_method(h_class, "turn_it_to_11",
- CLS_METHOD_RD | CLS_METHOD_WR | CLS_METHOD_PROMOTE,
- turn_it_to_11, &h_turn_it_to_11);
-
- // counter-examples
- cls_register_cxx_method(h_class, "bad_reader", CLS_METHOD_WR,
- bad_reader, &h_bad_reader);
- cls_register_cxx_method(h_class, "bad_writer", CLS_METHOD_RD,
- bad_writer, &h_bad_writer);
-
- // A PGLS filter
- cls_register_cxx_filter(h_class, "hello", hello_filter);
-}
Code Review / stor4nfv.git / blobdiff