From ce270ad7d8136aac47a802a9a72c011344f90527 Mon Sep 17 00:00:00 2001
From: Thomas White <taw@physics.org>
Date: Wed, 5 May 2021 17:07:13 +0200
Subject: indexamajig: Add --zmq-request

This (re-)adds the ability to get data via a request/reply socket.
See afcb7b568947c for when it was removed.
---
 src/im-zmq.c | 63 +++++++++++++++++++++++++++++++++++++++++++++---------------
 1 file changed, 47 insertions(+), 16 deletions(-)

(limited to 'src/im-zmq.c')

diff --git a/src/im-zmq.c b/src/im-zmq.c
index be3bc544..c2d386cf 100644
--- a/src/im-zmq.c
+++ b/src/im-zmq.c
@@ -52,12 +52,14 @@ struct im_zmq
 	void *ctx;
 	void *socket;
 	zmq_msg_t msg;
+	const char *request_str;
 };
 
 
 struct im_zmq *im_zmq_connect(const char *zmq_address,
                               char **subscriptions,
-                              int n_subscriptions)
+                              int n_subscriptions,
+                              const char *zmq_request)
 {
 	struct im_zmq *z;
 	int i;
@@ -68,30 +70,46 @@ struct im_zmq *im_zmq_connect(const char *zmq_address,
 	z->ctx = zmq_ctx_new();
 	if ( z->ctx == NULL ) return NULL;
 
-	z->socket = zmq_socket(z->ctx, ZMQ_SUB);
+	if ( zmq_request == NULL ) {
+		STATUS("Connecting ZMQ subscriber to '%s'\n", zmq_address);
+		z->socket = zmq_socket(z->ctx, ZMQ_SUB);
+	} else {
+		STATUS("Connecting ZMQ requester to '%s'\n", zmq_address);
+		z->socket = zmq_socket(z->ctx, ZMQ_REQ);
+	}
 	if ( z->socket == NULL ) return NULL;
 
-	STATUS("Connecting to ZMQ at '%s'\n", zmq_address);
 	if ( zmq_connect(z->socket, zmq_address) == -1 ) {
 		ERROR("ZMQ connection failed: %s\n", zmq_strerror(errno));
 		return NULL;
 	}
 
-	if ( n_subscriptions == 0 ) {
-		ERROR("WARNING: No ZeroMQ subscriptions.  You should probably "
-		      "try again with --zmq-subscribe.\n");
-	}
+	if ( zmq_request == NULL ) {
 
-	for ( i=0; i<n_subscriptions; i++ ) {
-		STATUS("Subscribing to '%s'\n", subscriptions[i]);
-		if ( zmq_setsockopt(z->socket, ZMQ_SUBSCRIBE,
-		                    subscriptions[i],
-		                    strlen(subscriptions[i])) )
-		{
-			ERROR("ZMQ subscription failed: %s\n",
-			      zmq_strerror(errno));
-			return NULL;
+		/* SUB mode */
+		if ( n_subscriptions == 0 ) {
+			ERROR("WARNING: No ZeroMQ subscriptions.  You should "
+			      "probably try again with --zmq-subscribe.\n");
 		}
+		for ( i=0; i<n_subscriptions; i++ ) {
+			STATUS("Subscribing to '%s'\n", subscriptions[i]);
+			if ( zmq_setsockopt(z->socket, ZMQ_SUBSCRIBE,
+			                    subscriptions[i],
+			                    strlen(subscriptions[i])) )
+			{
+				ERROR("ZMQ subscription failed: %s\n",
+				      zmq_strerror(errno));
+				return NULL;
+			}
+		}
+
+		z->request_str = NULL;
+
+	} else {
+
+		/* REQ mode */
+		z->request_str = zmq_request;
+
 	}
 
 	return z;
@@ -103,6 +121,19 @@ void *im_zmq_fetch(struct im_zmq *z, size_t *pdata_size)
 	int msg_size;
 	void *data_copy;
 
+	if ( z->request_str != NULL ) {
+
+		/* Send the request */
+		if ( zmq_send(z->socket, z->request_str,
+		              strlen(z->request_str), 0) == -1 )
+		{
+			ERROR("ZMQ message send failed: %s\n",
+			      zmq_strerror(errno));
+			return NULL;
+		}
+	}
+
+	/* Receive message */
 	zmq_msg_init(&z->msg);
 	msg_size = zmq_msg_recv(&z->msg, z->socket, 0);
 	if ( msg_size == -1 ) {
-- 
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