libglusterfs: replace default functions with generated versions

Replacing repetitive code like this with code generated from a more
compact "canonical" definition carries several advantages.

 * Ease the process of adding new fops (e.g. GF_FOP_IPC).

 * Ease the process of making global changes to existing fops (e.g.
   adding "xdata").

 * Ensure strict consistency between all of the pieces that must be
   compatible with each other, through both kinds of changes.

What we have right now is just a start.  The above benefits will only
truly be realized when we use the same definitions to generate stubs,
syncops, and perhaps even parts of gfapi or glupy.

This same infrastructure can also be used to reduce code duplication and
potential for error in many of our translators.  NSR already uses a
similar technique, using a few hundred lines of templates to generate a
few *thousand* lines of code.  The ability to make a global "aspect"
change (e.g. to quorum checking) in one place instead of seventy has
already been demonstrated there.

Other candidates for code generation include the AFR/EC transaction
infrastructure, or stub creation/resumption in io-threads.

Change-Id: If7d59de7a088848b557f5aea00741b4fe19017c1
BUG: 1271325
Signed-off-by: Jeff Darcy <jdarcy@redhat.com>
Reviewed-on: http://review.gluster.org/9411
Tested-by: Gluster Build System <jenkins@build.gluster.com>
Tested-by: NetBSD Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>
Reviewed-by: Vijay Bellur <vbellur@redhat.com>

1 files changed, 185 insertions, 0 deletions

diff --git a/libglusterfs/src/defaults-tmpl.c b/libglusterfs/src/defaults-tmpl.c
new file mode 100644
index 00000000000..4d83368cc32
--- /dev/null
+++ b/libglusterfs/src/defaults-tmpl.c
@@ -0,0 +1,185 @@
+/*
+  Copyright (c) 2008-2015 Red Hat, Inc. <http://www.redhat.com>
+  This file is part of GlusterFS.
+
+  This file is licensed to you under your choice of the GNU Lesser
+  General Public License, version 3 or any later version (LGPLv3 or
+  later), or the GNU General Public License, version 2 (GPLv2), in all
+  cases as published by the Free Software Foundation.
+*/
+
+/* libglusterfs/src/defaults.c:
+   This file contains functions, which are used to fill the 'fops', 'cbk'
+   structures in the xlator structures, if they are not written. Here, all the
+   function calls are plainly forwared to the first child of the xlator, and
+   all the *_cbk function does plain STACK_UNWIND of the frame, and returns.
+
+   This function also implements *_resume () functions, which does same
+   operation as a fop().
+
+   All the functions are plain enough to understand.
+*/
+
+#ifndef _CONFIG_H
+#define _CONFIG_H
+#include "config.h"
+#endif
+
+#include "xlator.h"
+#include "defaults.h"
+
+#pragma generate
+
+struct xlator_fops _default_fops = {
+        .create = default_create,
+        .open = default_open,
+        .stat = default_stat,
+        .readlink = default_readlink,
+        .mknod = default_mknod,
+        .mkdir = default_mkdir,
+        .unlink = default_unlink,
+        .rmdir = default_rmdir,
+        .symlink = default_symlink,
+        .rename = default_rename,
+        .link = default_link,
+        .truncate = default_truncate,
+        .readv = default_readv,
+        .writev = default_writev,
+        .statfs = default_statfs,
+        .flush = default_flush,
+        .fsync = default_fsync,
+        .setxattr = default_setxattr,
+        .getxattr = default_getxattr,
+        .fsetxattr = default_fsetxattr,
+        .fgetxattr = default_fgetxattr,
+        .removexattr = default_removexattr,
+        .fremovexattr = default_fremovexattr,
+        .opendir = default_opendir,
+        .readdir = default_readdir,
+        .readdirp = default_readdirp,
+        .fsyncdir = default_fsyncdir,
+        .access = default_access,
+        .ftruncate = default_ftruncate,
+        .fstat = default_fstat,
+        .lk = default_lk,
+        .inodelk = default_inodelk,
+        .finodelk = default_finodelk,
+        .entrylk = default_entrylk,
+        .fentrylk = default_fentrylk,
+        .lookup = default_lookup,
+        .rchecksum = default_rchecksum,
+        .xattrop = default_xattrop,
+        .fxattrop = default_fxattrop,
+        .setattr = default_setattr,
+        .fsetattr = default_fsetattr,
+	.fallocate = default_fallocate,
+	.discard = default_discard,
+        .zerofill = default_zerofill,
+        .ipc = default_ipc,
+
+        .getspec = default_getspec,
+};
+struct xlator_fops *default_fops = &_default_fops;
+
+
+/*
+ * Remaining functions don't follow the fop calling conventions, so they're
+ * not generated.
+ */
+
+int32_t
+default_forget (xlator_t *this, inode_t *inode)
+{
+        gf_log_callingfn (this->name, GF_LOG_WARNING, "xlator does not "
+                          "implement forget_cbk");
+        return 0;
+}
+
+
+int32_t
+default_releasedir (xlator_t *this, fd_t *fd)
+{
+        gf_log_callingfn (this->name, GF_LOG_WARNING, "xlator does not "
+                          "implement releasedir_cbk");
+        return 0;
+}
+
+int32_t
+default_release (xlator_t *this, fd_t *fd)
+{
+        gf_log_callingfn (this->name, GF_LOG_WARNING, "xlator does not "
+                          "implement release_cbk");
+        return 0;
+}
+
+/* notify */
+int
+default_notify (xlator_t *this, int32_t event, void *data, ...)
+{
+        switch (event) {
+        case GF_EVENT_PARENT_UP:
+        case GF_EVENT_PARENT_DOWN:
+        {
+                xlator_list_t *list = this->children;
+
+                while (list) {
+                        xlator_notify (list->xlator, event, this);
+                        list = list->next;
+                }
+        }
+        break;
+        case GF_EVENT_CHILD_CONNECTING:
+        case GF_EVENT_CHILD_MODIFIED:
+        case GF_EVENT_CHILD_DOWN:
+        case GF_EVENT_CHILD_UP:
+        case GF_EVENT_AUTH_FAILED:
+        {
+                xlator_list_t *parent = this->parents;
+
+                /*
+                 * Handle case of CHILD_* & AUTH_FAILED event specially, send
+                 * it to fuse.
+                 */
+                if (!parent && this->ctx && this->ctx->master) {
+                        xlator_notify (this->ctx->master, event, this->graph,
+                                       NULL);
+                }
+
+                while (parent) {
+                        if (parent->xlator->init_succeeded)
+                                xlator_notify (parent->xlator, event,
+                                               this, NULL);
+                        parent = parent->next;
+                }
+        }
+        break;
+        default:
+        {
+                xlator_list_t *parent = this->parents;
+
+                while (parent) {
+                        if (parent->xlator->init_succeeded)
+                                xlator_notify (parent->xlator, event,
+                                               this, NULL);
+                        parent = parent->next;
+                }
+        }
+        /*
+         * Apparently our picky-about-everything else coding standard allows
+         * adjacent same-indendation-level close braces.  Clearly it has
+         * nothing to do with readability.
+         */
+        }
+
+        return 0;
+}
+
+int32_t
+default_mem_acct_init (xlator_t *this)
+{
+        int     ret = -1;
+
+        ret = xlator_mem_acct_init (this, gf_common_mt_end);
+
+        return ret;
+}