Support deserialization of most state (curl input is not really good yet).

[cubemap] / cubemap.cpp

diff --git a/cubemap.cpp b/cubemap.cpp
index 692d48baf1d9e507d36926aa10a7f35f7d8847b1..ed615a876574a8334757bd226529f58814e3ef70 100644 (file)
--- a/cubemap.cpp
+++ b/cubemap.cpp
@@ -9,6 +9,7 @@
 #include <sys/types.h>
 #include <sys/ioctl.h>
 #include <sys/epoll.h>
+#include <signal.h>
 #include <errno.h>
 #include <vector>
 #include <string>
@@ -17,6 +18,7 @@
 #include "metacube.h"
 #include "server.h"
 #include "input.h"
+#include "state.pb.h"
 
 #define NUM_SERVERS 4
 #define STREAM_ID "stream"
@@ -26,6 +28,12 @@
 using namespace std;
 
 Server *servers = NULL;
+volatile bool hupped = false;
+
+void hup(int ignored)
+{
+       hupped = true;
+}
 
 int create_server_socket(int port)
 {
@@ -97,24 +105,154 @@ void *acceptor_thread_run(void *arg)
        }
 }
 
+// Serialize the given state to a file descriptor, and return the (still open)
+// descriptor.
+int make_tempfile(const CubemapStateProto &state)
+{
+       char tmpl[] = "/tmp/cubemapstate.XXXXXX";
+       int state_fd = mkstemp(tmpl);
+       if (state_fd == -1) {
+               perror("mkstemp");
+               exit(1);
+       }
+
+       string serialized;
+       state.SerializeToString(&serialized);
+
+       const char *ptr = serialized.data();
+       size_t to_write = serialized.size();
+       while (to_write > 0) {
+               ssize_t ret = write(state_fd, ptr, to_write);
+               if (ret == -1) {
+                       perror("write");
+                       exit(1);
+               }
+
+               ptr += ret;
+               to_write -= ret;
+       }
+
+       return state_fd;
+}
+
+// Read the state back from the file descriptor made by make_tempfile,
+// and close it.
+CubemapStateProto read_tempfile(int state_fd)
+{
+       if (lseek(state_fd, 0, SEEK_SET) == -1) {
+               perror("lseek");
+               exit(1);
+       }
+
+       string serialized;
+       char buf[4096];
+       for ( ;; ) {
+               ssize_t ret = read(state_fd, buf, sizeof(buf));
+               if (ret == -1) {
+                       perror("read");
+                       exit(1);
+               }
+               if (ret == 0) {
+                       // EOF.
+                       break;
+               }
+
+               serialized.append(string(buf, buf + ret));
+       }
+
+       close(state_fd);  // Implicitly deletes the file.
+
+       CubemapStateProto state;
+       if (!state.ParseFromString(serialized)) {
+               fprintf(stderr, "PANIC: Failed deserialization of state.\n");
+               exit(1);
+       }
+
+       return state;
+}
+
 int main(int argc, char **argv)
 {
+       fprintf(stderr, "\nCubemap starting.\n");
+               
        servers = new Server[NUM_SERVERS];
+
+       int server_sock;
+       if (argc == 3 && strcmp(argv[1], "-state") == 0) {
+               fprintf(stderr, "Deserializing state from previous process... ");
+               int state_fd = atoi(argv[2]);
+               CubemapStateProto loaded_state = read_tempfile(state_fd);
+
+               // Deserialize the streams.
+               for (int i = 0; i < loaded_state.streams_size(); ++i) {
+                       for (int j = 0; j < NUM_SERVERS; ++j) {
+                               servers[j].add_stream_from_serialized(loaded_state.streams(i));
+                       }
+               }
+
+               // Put back the existing clients. It doesn't matter which server we
+               // allocate them to, so just do round-robin.
+               for (int i = 0; i < loaded_state.clients_size(); ++i) {
+                       servers[i % NUM_SERVERS].add_client_from_serialized(loaded_state.clients(i));
+               }
+
+               // Deserialize the server socket.
+               server_sock = loaded_state.server_sock();
+
+               fprintf(stderr, "done.\n");
+       } else {
+               // TODO: This should come from a config file.
+               server_sock = create_server_socket(PORT);
+               for (int i = 0; i < NUM_SERVERS; ++i) {
+                       servers[i].add_stream(STREAM_ID);
+               }
+       }
+
        for (int i = 0; i < NUM_SERVERS; ++i) {
-               servers[i].add_stream(STREAM_ID);
                servers[i].run();
        }
 
-       int server_sock = create_server_socket(PORT);
-
        pthread_t acceptor_thread;
        pthread_create(&acceptor_thread, NULL, acceptor_thread_run, reinterpret_cast<void *>(server_sock));
 
-       Input input(STREAM_ID);
-       input.run(STREAM_URL);
+       Input input(STREAM_ID, STREAM_URL);
+       input.run();
+
+       signal(SIGHUP, hup);
+
+       while (!hupped) {
+               usleep(100000);
+       }
 
+       input.stop();
+
+       CubemapStateProto state;
+       state.set_server_sock(server_sock);
        for (int i = 0; i < NUM_SERVERS; ++i) {
                servers[i].stop();
+
+               CubemapStateProto local_state = servers[i].serialize();
+
+               // The stream state should be identical between the servers, so we only store it once.
+               if (i == 0) {
+                       state.mutable_streams()->MergeFrom(local_state.streams());
+               }
+               for (int j = 0; j < local_state.clients_size(); ++j) {
+                       state.add_clients()->MergeFrom(local_state.clients(j));
+               }
        }
        delete[] servers;
+
+       fprintf(stderr, "Serializing state and re-execing...\n");
+       int state_fd = make_tempfile(state);
+
+       char buf[16];
+       sprintf(buf, "%d", state_fd);
+
+       for ( ;; ) {
+               execlp(argv[0], argv[0], "-state", buf, NULL);
+               perror("execlp");
+               fprintf(stderr, "PANIC: re-exec of %s failed. Waiting 0.2 seconds and trying again...\n", argv[0]);
+               usleep(200000);
+       }
 }