gfapi: add API to trigger events for debugging and troubleshooting

Introduce glfs_sysrq() as a generic API for triggering debug and
troubleshoot events. This interface will be used by the feature to get
statedumps for applications using libgfapi.

The current events that can be requested through this API are:
 - 'h'elp: log a mesage with all supported events
 - 's'tatedump: trigger a statedump for the passed glfs_t

In future, this API can be used by a CLI to trigger statedumps from
storage servers. At the moment it is limited to take statedumps, but it
is extensible to set the log-level, clear caches, force reconnects and
much more.

> BUG: 1169302
> Change-Id: I18858359a3957870cea5139c79efe1365a15a992
> Original-author: Poornima G <pgurusid@redhat.com>
> Signed-off-by: Niels de Vos <ndevos@redhat.com>
> Reviewed-on-master: http://review.gluster.org/16414
> Reviewed-by: Prashanth Pai <ppai@redhat.com>
> Reviewed-by: Kaleb KEITHLEY <kkeithle@redhat.com>

BUG: 1418981
Change-Id: I18858359a3957870cea5139c79efe1365a15a992
Signed-off-by: Shyam <srangana@redhat.com>
Reviewed-on: https://review.gluster.org/16600
Smoke: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Niels de Vos <ndevos@redhat.com>
NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>

1 files changed, 61 insertions, 3 deletions

diff --git a/api/src/glfs.c b/api/src/glfs.c
index 4559707c4e1..4aa9711c29f 100644
--- a/api/src/glfs.c
+++ b/api/src/glfs.c
@@ -40,12 +40,13 @@
 #include "common-utils.h"
 #include "syncop.h"
 #include "call-stub.h"
-#include "gfapi-messages.h"
+#include "hashfn.h"
+#include "rpc-clnt.h"
+#include "statedump.h"
 
+#include "gfapi-messages.h"
 #include "glfs.h"
 #include "glfs-internal.h"
-#include "hashfn.h"
-#include "rpc-clnt.h"
 
 
 static gf_boolean_t
@@ -1453,3 +1454,60 @@ pub_glfs_upcall_inode_get_oldpstat (struct glfs_upcall_inode *arg)
         return &arg->oldp_buf;
 }
 GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_upcall_inode_get_oldpstat, 3.7.16);
+
+
+/* definitions of the GLFS_SYSRQ_* chars are in glfs.h */
+static struct glfs_sysrq_help {
+        char  sysrq;
+        char *msg;
+} glfs_sysrq_help[] = {
+        { GLFS_SYSRQ_HELP,      "(H)elp" },
+        { GLFS_SYSRQ_STATEDUMP, "(S)tatedump" },
+        { 0,                    NULL }
+};
+
+int
+pub_glfs_sysrq (struct glfs *fs, char sysrq)
+{
+        glusterfs_ctx_t  *ctx = NULL;
+        int               ret = 0;
+
+        if (!fs || !fs->ctx) {
+                ret = -1;
+                errno = EINVAL;
+                goto out;
+        }
+
+        ctx = fs->ctx;
+
+        switch (sysrq) {
+        case GLFS_SYSRQ_HELP:
+        {
+                char msg[1024]; /* help text should not exceed 1024 chars */
+                struct glfs_sysrq_help *usage;
+
+                msg[0] = '\0';
+                for (usage = glfs_sysrq_help; usage->sysrq; usage++) {
+                        strncat (msg, usage->msg, 1024);
+                        strncat (msg, " ", 1024);
+                }
+
+                /* not really an 'error', but make sure it gets logged */
+                gf_log ("glfs", GF_LOG_ERROR, "available events: %s", msg);
+
+                break;
+        }
+        case GLFS_SYSRQ_STATEDUMP:
+                gf_proc_dump_info (SIGUSR1, ctx);
+                break;
+        default:
+                gf_msg ("glfs", GF_LOG_ERROR, ENOTSUP, API_MSG_INVALID_ENTRY,
+                        "'%c' is not a valid sysrq", sysrq);
+                errno = ENOTSUP;
+                ret = -1;
+        }
+out:
+        return ret;
+}
+
+GFAPI_SYMVER_PUBLIC_DEFAULT(glfs_sysrq, 3.10.0);