--- /dev/null
+#include <unistd.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <sys/select.h>
+#include <malloc.h>
+
+#define sint64_t int64_t
+
+#include "v3_user_keyed_stream.h"
+
+void usage()
+{
+ fprintf(stderr,"v3_user_keyed_stream_example /dev/v3-vm0 user:mystreamtype:mystream busywait|select\n");
+}
+
+
+int do_work(struct palacios_user_keyed_stream_op *req,
+ struct palacios_user_keyed_stream_op **resp)
+{
+ uint64_t datasize;
+
+ //
+ //
+ // Process request here
+ //
+ // req->len : total structure length
+ // req->type : request type (currently open/close key and read/write key
+ // req->xfer : unused
+ // req->user_key : the opaque key previously provided by you by an open key
+ // req->buf_len : length of data
+ // req->buf : buffer (contains key name (open key) or value (write key))
+ //
+
+ // now built a response
+ *resp = malloc(sizeof(struct palacios_user_keyed_stream_op) + datasize);
+ (*resp)->len = sizeof(struct palacios_user_keyed_stream_op) + datasize;
+ (*resp)->buf_len = datasize;
+ (*resp)->type = req->type;
+ (*resp)->user_key = req->user_key;
+
+ //
+ // The response
+ //
+ // resp->len : total structure length
+ // resp->type : response type - must match the request
+ // resp->xfer : contains the size of data read or written (in read key or write key)
+ // resp->user_key : unused
+ // resp->buf_len : length of data following
+ // resp->buf : buffer (contains the data (read key))
+
+
+ return 0;
+}
+
+int main(int argc, char *argv[])
+{
+ int devfd;
+ int mode=0;
+ char *vm, *url;
+
+ if (argc!=4) {
+ usage();
+ exit(-1);
+ }
+
+ vm=argv[1];
+ url=argv[2];
+ mode = argv[3][0]=='s';
+
+ // The URL should begin with user:
+ // the remainder can be used to demultiplex internally
+ // for example user:file:foo might refer to a user-side file-based implementation
+ //
+
+ if (strncmp(url,"user:",5)) {
+ fprintf(stderr, "URL %s is not a user: url\n");
+ exit(-1);
+ }
+
+ fprintf(stderr,"Attempting to attach to vm %s as url %s\n", vm, url);
+
+ if ((devfd = v3_user_keyed_stream_attach(vm,url))<0) {
+ perror("failed to attach");
+ exit(-1);
+ }
+
+ fprintf(stderr,"Attachment succeeded, I will now operate in %s mode\n", mode==0 ? "busywait" : "select");
+
+ if (mode==0) {
+ //busywait
+
+ struct palacios_user_keyed_stream_op *req;
+ struct palacios_user_keyed_stream_op *resp;
+ uint64_t datasize;
+
+ while (1) {
+ while (!(v3_user_keyed_stream_have_request(devfd))) {
+ }
+ v3_user_keyed_stream_pull_request(devfd, &req);
+
+ do_work(req, &resp);
+
+ v3_user_keyed_stream_push_response(devfd, resp);
+
+ free(resp);
+ free(req);
+ }
+ } else {
+
+ struct palacios_user_keyed_stream_op *req;
+ struct palacios_user_keyed_stream_op *resp;
+ uint64_t datasize;
+ fd_set readset;
+ int rc;
+
+ // select-based operation so that you can wait for multiple things
+
+ while (1) {
+ FD_ZERO(&readset);
+ FD_SET(devfd,&readset);
+
+ rc = select(devfd+1, &readset, 0, 0, 0); // pick whatever you want to select on, just include devfd
+
+ if (rc>0) {
+ if (FD_ISSET(devfd,&readset)) {
+ // a request is read for us!
+ v3_user_keyed_stream_pull_request(devfd, &req);
+
+ do_work(req, &resp);
+
+ v3_user_keyed_stream_push_response(devfd, resp);
+
+ free(resp);
+ free(req);
+ }
+ }
+ }
+ }
+
+ v3_user_keyed_stream_detatch(devfd);
+
+ return 0;
+
+}
