Hi Sean,
To preload distributed database servers in a fine-grained way, we have
made the following three changes to the rsocket code base:
1) intercept a single process when the program has multiple processes
(src/preload.c)
2) invoke rlisten() multiple times from different listening threads
for the same endpoint without an error (src/rsocket.c)
3) continue waiting for a completion event up on interruption
(src/rsocket.c)
We have ensured that these changes are gated by runtime parameters,
so the existing logic can work as before. For your and community
perusal, I have attached the changes at the end of this message.
Could you please go through the provided changes and ensure that
they are part of the regular rsocket head stream.
Please let me know if you have any clarifications or suggestions.
Thank You.
- Sreedhar
Subject: [patch 1/3] subsystem: RDMA CM
commit 725d209ea390c643447c337b178442e5ef7b8b50
Author: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Date: Tue Aug 5 16:18:58 2014 +0530
By default the R-Sockets pre-loading library intercepts all the
stream
and datagram sockets belonging to a launched program processes and
threads.
However, distributed application and database servers may require
fine
grained interception to ensure that only the processes which are
listening
for remote connections on the RDMA transport need to be enabled with
RDMA
while remaining can continue to use TCP as before. This allows
proper
communication happening between various server components locally.
A configuration file based mechanism is introduced to facilitate
this
fine grained interception mechanism. As part of preload
initialization,
the configuration file is scanned and an in-memory record store is
created
with all the entries found. When a request is made to intercept a
socket,
its attributes are cross checked with stored records to see whether
we
should proceed with rsocket switch over.
Note: Right now, the fine grained interception mechanism is enabled
only
for newly created sockets. Going forward, this can be extened
to
select connections based on the specified host/IP addresses
and
ports as well.
"preload_config" is the name of the configuration file which should
exist
in the default configuration location (usually the full path to this
configuration file is:
<install-root>/etc/rdma/rsocket/preload_config)
of an installed rsocket library.
The sample format for this configuration file is shown below:
@#
@# Sample config file for preloading in a program specific way
@#
@# Each line entry should have the following format:
@#
@# prog_name <space> dom_spec <space> type_spec <space> proto_spec
@#
@# where,
@#
@# prog_name - program or command name (string without spaces)
@# dom_spec - one or more socket domain strings separated by
commas
@# - format: {*|domain,[,domain,...]}
@# - '*' means any valid domain
@# - valid domains: inet/inet6/ib
@# type_spec - one or more socket type strings separated by commas
@# - format: {*|type[,type,...]}
@# - '*' means any valid type
@# - valid types: stream/dgram
@# proto_spec - one or more socket protocol strings separated by
commas
@# - format: {*|protocol[,protocol,...]}
@# - '*' means any valid protocol
@# - valid protocols: tcp/udp
@# <space> - one ore more tab or space characters
@#
@# Note:
@# Lines beginning with '#' character are treated as comments.
@# Comments at the end of an entry are allowed and should be
preceded
@# by '#' character.
@# Blank lines are ignored.
@
@progA inet stream tcp # intercept progA's internet stream sockets
@progB inet6 dgram udp # intercept progB's ipv6 datagram sockets
@progC * * * # intercept progC's sockets
Signed-off-by: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Pradeep Satyanarayana <pradeeps@xxxxxxxxxxxxxxxxxx>
---
diff --git a/src/preload.c b/src/preload.c
index fb2149b..8c043aa 100644
--- a/src/preload.c
+++ b/src/preload.c
@@ -50,6 +50,8 @@
#include <netinet/tcp.h>
#include <unistd.h>
#include <semaphore.h>
+#include <ctype.h>
+#include <stdlib.h>
#include <rdma/rdma_cma.h>
#include <rdma/rdma_verbs.h>
@@ -57,6 +59,10 @@
#include "cma.h"
#include "indexer.h"
+#ifndef LINE_MAX
+#define LINE_MAX 2048
+#endif /* LINE_MAX */
+
struct socket_calls {
int (*socket)(int domain, int type, int protocol);
int (*bind)(int socket, const struct sockaddr *addr, socklen_t
addrlen);
@@ -122,6 +128,227 @@ struct fd_info {
atomic_t refcnt;
};
+typedef struct {
+ char *name;
+ uint32_t domain;
+ uint32_t type;
+ uint32_t protocol;
+} config_entry_t;
+
+static config_entry_t *entryp = NULL;
+static int16_t nentries = 0;
+static int16_t config_scanned = 0;
+static int16_t config_avail = 0;
+extern char *program_invocation_short_name;
+
+/* scan preload configuration file and create
+ * in-memory config store
+ * should be called only once under lock
+ */
+static int scan_preload_config(void)
+{
+ FILE *fp;
+ char line[LINE_MAX];
+ char *lp, *cp, *str1, *str2;
+ char *token, *subtoken, *saveptr1, *saveptr2;
+ int i, j, ret = 0;
+
+ fp = fopen(RS_CONF_DIR "/preload_config", "r");
+ if (fp == NULL) {
+ return -1;
+ }
+
+ while ((lp = fgets(line, LINE_MAX, fp)) != NULL) {
+
+ /* trim white space at the beginning of each line */
+ while (*lp != '\0') {
+ if (isspace(*lp)) {
+ lp++;
+ continue;
+ } else {
+ break;
+ }
+ }
+
+ /* skip comment and blank lines */
+ if (*lp == '\0' || *lp == '#') {
+ continue;
+ }
+
+ /* trim comments and newlines at the end of each line */
+ if ((cp = strpbrk(lp, "#\n")) != NULL) {
+ *cp = '\0';
+ }
+
+ /* now allocate memory for new configuration entry */
+ entryp = (config_entry_t *) realloc(entryp, (nentries + 1) *
sizeof(config_entry_t));
+ if (!entryp) {
+ ret = -1;
+ goto scan_done;
+ }
+ memset(entryp + nentries, '\0', sizeof(config_entry_t));
+
+ /* tokenize the retrieved line and parse individual fields */
+ for (i = 1, str1 = lp; ; i++, str1 = NULL) {
+ token = strtok_r(str1, " \t", &saveptr1);
+ if (token == NULL) {
+ break;
+ }
+
+ /* first field should contain program name */
+ if (i == 1) {
+ entryp[nentries].name = (char *) malloc((strlen(token) +
1));
+ if (!entryp[nentries].name) {
+ ret = -1;
+ goto scan_done;
+ }
+ memcpy(entryp[nentries].name, token, strlen(token) + 1);
+ continue;
+ }
+
+ /* second field onwards can contain multiple entries
separate by comma */
+ for (j = 1, str2 = token; ; j++, str2 = NULL) {
+ subtoken = strtok_r(str2, ",", &saveptr2);
+ if (subtoken == NULL) {
+ break;
+ }
+
+ /* second field is socket domain
+ * rsocket currently recognizes only AF_INET, AF_INET6
and AF_IB domains
+ * '*' implies all the valid domains
+ */
+ if (i == 2) {
+ if (*subtoken == '*') {
+ entryp[nentries].domain |= (1 << AF_INET);
+ entryp[nentries].domain |= (1 << AF_INET6);
+ entryp[nentries].domain |= (1 << AF_IB);
+ break;
+ } else if (strcmp(subtoken, "inet6") == 0) {
+ entryp[nentries].domain |= (1 << AF_INET6);
+ } else if (strcmp(subtoken, "inet") == 0) {
+ entryp[nentries].domain |= (1 << AF_INET);
+ } else if (strcmp(subtoken, "ib") == 0) {
+ entryp[nentries].domain |= (1 << AF_IB);
+ }
+ continue;
+ }
+
+ /* third field is socket type
+ * rsocket currently recognizes only SOCK_STREAM and
SOCK_DGRAM types
+ * '*' implies all the valid types
+ */
+ if (i == 3) {
+ if (*subtoken == '*') {
+ entryp[nentries].type |= (1 << SOCK_STREAM);
+ entryp[nentries].type |= (1 << SOCK_DGRAM);
+ break;
+ } else if (strcmp(subtoken, "stream") == 0) {
+ entryp[nentries].type |= (1 << SOCK_STREAM);
+ } else if (strcmp(subtoken, "dgram") == 0) {
+ entryp[nentries].type |= (1 << SOCK_DGRAM);
+ }
+ continue;
+ }
+
+ /* fourth field is socket protocol
+ * rsocket currently recgonizes only IPPROTO_TCP and
IPPROTO_UDP protocols
+ * '*' implies all the valid protocols
+ */
+ if (i == 4) {
+ if (*subtoken == '*') {
+ entryp[nentries].protocol |= (1 << IPPROTO_TCP);
+ entryp[nentries].protocol |= (1 << IPPROTO_UDP);
+ break;
+ } else if (strcmp(subtoken, "tcp") == 0) {
+ entryp[nentries].protocol |= (1 << IPPROTO_TCP);
+ } else if (strcmp(subtoken, "udp") == 0) {
+ entryp[nentries].protocol |= (1 << IPPROTO_UDP);
+ }
+ continue;
+ }
+ }
+ }
+ nentries += 1;
+ }
+
+scan_done:
+ fclose(fp);
+ return ret;
+}
+
+/* free in-memory config store
+ * should be called only once during finalization
+ */
+static void free_preload_config(void)
+{
+ int i;
+
+ if (entryp) {
+ for (i = 0; i < nentries; i++) {
+ if (entryp[i].name) {
+ free(entryp[i].name);
+ }
+ }
+ free(entryp);
+ }
+
+ return;
+}
+
+/* check whether interception is required for this socket
+ * compares the provided attributes with that available in the
in-memory
+ * data store for the current process
+ * sets-up in-memory config store if it's already not done
+ */
+static int intercept_socket(int domain, int type, int protocol)
+{
+ int i;
+
+ if (!config_scanned) {
+ pthread_mutex_lock(&mut);
+ if (scan_preload_config() == 0) {
+ config_avail = 1;
+ }
+ if (entryp) {
+ atexit(free_preload_config);
+ }
+ config_scanned = 1;
+ pthread_mutex_unlock(&mut);
+ }
+
+ if (!config_avail) {
+ return -1;
+ }
+
+ /* locate the config entry */
+ for (i = 0; i < nentries; i++) {
+ if (strncmp(entryp[i].name, program_invocation_short_name,
strlen(entryp[i].name)) == 0) {
+ break;
+ }
+ }
+ if (i == nentries) {
+ return 0;
+ }
+
+ /* match domain field */
+ if (!(entryp[i].domain & (1 << domain))) {
+ return 0;
+ }
+
+ /* match type field */
+ if (!(entryp[i].type & (1 << type))) {
+ return 0;
+ }
+
+ /* match protocol field only if protocol is specified */
+ if (protocol && !(entryp[i].protocol & (1 << protocol))) {
+ return 0;
+ }
+
+ /* entry matched */
+ return 1;
+}
+
static int fd_open(void)
{
struct fd_info *fdi;
@@ -404,6 +631,10 @@ int socket(int domain, int type, int protocol)
static __thread int recursive;
int index, ret;
+ if (intercept_socket(domain, type, protocol) == 0) {
+ goto real;
+ }
+
if (recursive)
goto real;
Subject: [patch 2/3] subsystem: RDMA CM
commit bf77b79be41b9ed288be6c7e858d463838febc84
Author: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Date: Tue Aug 5 16:38:05 2014 +0530
Some complex server class applications start multiple listening
threads
to receive client connection requests simultaneously from different
sources.
When rsocket tries to intercept sockets belonging to such
applications,
the listen() call made multiple times from different listening
threads
should not result in error on par with the corresponding TCP
behavior.
The return value of rlisten() is modified to ensure that it wouldn't
bail out when it is invoked more than once with the same socket
attributes
from different listening threads. This behavior is gated by a
runtime
parameter 'multi_listeners' with the associated configuration file
so it
does not affect in any way the rest of rsocket applications.
Signed-off-by: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Pradeep Satyanarayana <pradeeps@xxxxxxxxxxxxxxxxxx>
---
diff --git a/src/rsocket.c b/src/rsocket.c
index 7007897..3879a70 100644
--- a/src/rsocket.c
+++ b/src/rsocket.c
@@ -115,6 +115,7 @@ static uint16_t def_rqsize = 384;
static uint32_t def_mem = (1 << 17);
static uint32_t def_wmem = (1 << 17);
static uint32_t polling_time = 10;
+static uint16_t multi_listeners = 0;
/*
* Immediate data format is determined by the upper bits
@@ -542,6 +543,11 @@ void rs_configure(void)
def_iomap_size = (uint8_t) rs_value_to_scale(
(uint16_t) rs_scale_to_value(def_iomap_size, 8), 8);
}
+
+ if ((f = fopen(RS_CONF_DIR "/multi_listeners", "r"))) {
+ (void) fscanf(f, "%hu", &multi_listeners);
+ fclose(f);
+ }
init = 1;
out:
pthread_mutex_unlock(&mut);
@@ -1175,8 +1181,12 @@ int rlisten(int socket, int backlog)
if (!rs)
return ERR(EBADF);
ret = rdma_listen(rs->cm_id, backlog);
- if (!ret)
+ if (!ret) {
+ rs->state = rs_listening;
+ } else if (multi_listeners == 1 && errno == EINVAL) {
rs->state = rs_listening;
+ ret = 0;
+ }
return ret;
}
Subject: [patch 3/3] subsystem: RDMA CM
commit 275aafe76c98718ad6989cbe1cf35fb82e36cd2c
Author: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Date: Tue Aug 5 16:45:41 2014 +0530
While waiting for a completion queue event, rsocket's logic by
default
bails out when interrupted. Because of this, on the passive side
ongoing connection establishments are abruptly terminated without
fully accepting the incoming connection requests.
The solution is to modify the completion event waiting logic to
ensure
that it retries for the event upon interruption instead of returning
with an error. This behavior is gated by a runtime parameter
'restart_onintr' with the associated configuration file so it does
not affect in any way the rest of rsocket applications.
Signed-off-by: Sreedhar Kodali <srkodali@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Pradeep Satyanarayana <pradeeps@xxxxxxxxxxxxxxxxxx>
---
diff --git a/src/rsocket.c b/src/rsocket.c
index 3879a70..c7e5b11 100644
--- a/src/rsocket.c
+++ b/src/rsocket.c
@@ -116,6 +116,7 @@ static uint32_t def_mem = (1 << 17);
static uint32_t def_wmem = (1 << 17);
static uint32_t polling_time = 10;
static uint16_t multi_listeners = 0;
+static uint16_t restart_onintr = 0;
/*
* Immediate data format is determined by the upper bits
@@ -548,6 +549,11 @@ void rs_configure(void)
(void) fscanf(f, "%hu", &multi_listeners);
fclose(f);
}
+
+ if ((f = fopen(RS_CONF_DIR "/restart_onintr", "r"))) {
+ (void) fscanf(f, "%hu", &restart_onintr);
+ fclose(f);
+ }
init = 1;
out:
pthread_mutex_unlock(&mut);
@@ -1973,10 +1979,14 @@ static int rs_get_cq_event(struct rsocket *rs)
if (!rs->cq_armed)
return 0;
+resume_get_cq_event:
ret = ibv_get_cq_event(rs->cm_id->recv_cq_channel, &cq, &context);
if (!ret) {
ibv_ack_cq_events(rs->cm_id->recv_cq, 1);
rs->cq_armed = 0;
+ } else if (restart_onintr == 1 && errno == EINTR) {
+ errno = 0;
+ goto resume_get_cq_event;
} else if (errno != EAGAIN) {
rs->state = rs_error;
}
--
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