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>

7 files changed, 185 insertions, 4 deletions

diff --git a/api/src/gfapi-messages.h b/api/src/gfapi-messages.h
index 5deef15e3ae..6e131b5a295 100644
--- a/api/src/gfapi-messages.h
+++ b/api/src/gfapi-messages.h
@@ -40,7 +40,7 @@
  */
 
 #define GLFS_GFAPI_BASE             GLFS_MSGID_COMP_API
-#define GLFS_NUM_MESSAGES           48
+#define GLFS_NUM_MESSAGES           49
 #define GLFS_MSGID_END              (GLFS_GFAPI_BASE + GLFS_NUM_MESSAGES + 1)
 /* Messages with message IDs */
 #define glfs_msg_start_x GLFS_GFAPI_BASE, "Invalid: Start of messages"
@@ -94,6 +94,7 @@
 #define API_MSG_ALLOC_FAILED                    (GLFS_GFAPI_BASE + 46)
 #define API_MSG_CREATE_HANDLE_FAILED            (GLFS_GFAPI_BASE + 47)
 #define API_MSG_INODE_LINK_FAILED               (GLFS_GFAPI_BASE + 48)
+#define API_MSG_STATEDUMP_FAILED                (GLFS_GFAPI_BASE + 49)
 
 /*------------*/
 #define glfs_msg_end_x GLFS_MSGID_END, "Invalid: End of messages"
diff --git a/api/src/gfapi.aliases b/api/src/gfapi.aliases
index 83bfd1b6f85..d1bf2b22faa 100644
--- a/api/src/gfapi.aliases
+++ b/api/src/gfapi.aliases
@@ -156,3 +156,4 @@ _pub_glfs_upcall_inode_get_oldpobject _glfs_upcall_inode_get_oldpobject$GFAPI_3.
 _pub_glfs_upcall_inode_get_oldpstat _glfs_upcall_inode_get_oldpstat$GFAPI_3.7.16
 _pub_glfs_realpath _glfs_realpath$GFAPI_3.7.17
 
+_pub_glfs_sysrq _glfs_sysrq$GFAPI_3.10.0
diff --git a/api/src/gfapi.map b/api/src/gfapi.map
index 0567add0d73..48a6d90e922 100644
--- a/api/src/gfapi.map
+++ b/api/src/gfapi.map
@@ -194,3 +194,7 @@ GFAPI_3.7.17 {
 		glfs_realpath;
 } GFAPI_3.7.16;
 
+GFAPI_3.10.0 {
+	global:
+		glfs_sysrq;
+} GFAPI_3.7.17;
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);
diff --git a/api/src/glfs.h b/api/src/glfs.h
index 730cff51f5a..397bb878434 100644
--- a/api/src/glfs.h
+++ b/api/src/glfs.h
@@ -773,6 +773,23 @@ void glfs_free (void *ptr) __THROW
         GFAPI_PUBLIC(glfs_free, 3.7.16);
 
 /*
+ * glfs_sysrq: send a system request to the @fs instance
+ *
+ * Different commands for @sysrq are possible, the defines for these are listed
+ * below the function definition.
+ *
+ * This function always returns success if the @sysrq is recognized. The return
+ * value does not way anythin about the result of the @sysrq execution. Not all
+ * @sysrq command will be able to return a success/failure status.
+ */
+int glfs_sysrq (glfs_t *fs, char sysrq) __THROW
+        GFAPI_PUBLIC(glfs_sysrq, 3.10.0);
+
+#define GLFS_SYSRQ_HELP 'h' /* log a message with supported sysrq commands */
+#define GLFS_SYSRQ_STATEDUMP 's' /* create a statedump */
+
+
+/*
  * Nobody needs this call at all yet except for the test script.
  */
 int glfs_ipc (glfs_fd_t *fd, int cmd) __THROW
diff --git a/tests/basic/gfapi/glfs_sysrq.c b/tests/basic/gfapi/glfs_sysrq.c
new file mode 100644
index 00000000000..c843c2a3559
--- /dev/null
+++ b/tests/basic/gfapi/glfs_sysrq.c
@@ -0,0 +1,61 @@
+/** glfs_sysrq.c
+ *
+ * Simple test application to run all glfs_syqrq() debugging calls.
+ *
+ * Usage: ./glfs_sysrq <host> <volume> <logfile>
+ */
+#include <errno.h>
+#include <stdio.h>
+
+#include <glusterfs/api/glfs.h>
+
+int
+main (int argc, char *argv[])
+{
+        /* cmdline arguments */
+        char   *host    = NULL;
+        char   *volume  = NULL;
+        char   *logfile = NULL;
+
+        /* other variables */
+        glfs_t *fs      = NULL;
+        int     ret     = 0;
+
+        if (argc != 4) {
+                fprintf (stderr, "Usage: %s <host> <volume> <logfile>\n",
+                         argv[0]);
+                return -1;
+        }
+
+        host = argv[1];
+        volume = argv[2];
+        logfile = argv[3];
+
+        fs = glfs_new (volume);
+        if (!fs) {
+                return -1;
+        }
+
+        ret = glfs_set_logging (fs, logfile, 7);
+        if (ret < 0) {
+                return -1;
+        }
+
+        ret = glfs_set_volfile_server (fs, "tcp", host, 24007);
+        if (ret < 0) {
+                return -1;
+        }
+
+        ret = glfs_init (fs);
+        if (ret < 0) {
+                return -1;
+        }
+
+        /* checking of the results is easier in the script running this test */
+        glfs_sysrq (fs, GLFS_SYSRQ_HELP);
+        glfs_sysrq (fs, GLFS_SYSRQ_STATEDUMP);
+
+        glfs_fini (fs);
+
+        return 0;
+}
diff --git a/tests/basic/gfapi/glfs_sysrq.t b/tests/basic/gfapi/glfs_sysrq.t
new file mode 100755
index 00000000000..d1a0e9bc248
--- /dev/null
+++ b/tests/basic/gfapi/glfs_sysrq.t
@@ -0,0 +1,39 @@
+#!/bin/bash
+#
+# Run glfs_sysrq, a gfapi applications calling all glfs_sysrq() commands.
+# Each command generates a specific log message, or something else that can be
+# tested for existance.
+#
+
+. $(dirname $0)/../../include.rc
+. $(dirname $0)/../../volume.rc
+
+cleanup
+
+TEST glusterd
+TEST pidof glusterd
+TEST $CLI volume create $V0 $H0:$B0/brick1
+EXPECT 'Created' volinfo_field $V0 'Status'
+
+TEST $CLI volume start $V0;
+EXPECT 'Started' volinfo_field $V0 'Status'
+
+logdir=$(gluster --print-logdir)
+
+# clear all statedumps
+cleanup_statedump
+TEST ! test -e $statedumpdir/*.dump.*
+# vim friendly command */
+
+build_tester $(dirname $0)/glfs_sysrq.c -lgfapi
+TEST $(dirname $0)/glfs_sysrq $H0 $V0 $logdir/glfs_sysrq.log
+
+# check for the help message in the log
+TEST grep -q '"(H)elp"' $logdir/glfs_sysrq.log
+
+# see if there is a statedump
+TEST test -e $statedumpdir/*.dump.*
+# vim friendly command */
+
+cleanup_tester $(dirname $0)/glfs_sysrq
+cleanup