Implement TCP server mode.

This new mode works by first loading the model then listening for TCP
connections on a port. When a connection is received, arguments will be
parsed using a simple protocol:

- First the number of arguments will be read followed by a newline
  character.
- Then each argument will be read, separated by the 0 byte.
- With this we build an argument vector, similar to what is passed to
  the program entry point. We pass this to gpt_params_parse.

Finally `llama_main` will be executed with the input/output streams
connected to the socket.

Signed-off-by: Thiago Padilha <thiago@padilha.cc>

CMakeLists.txt

@@ -112,6 +112,10 @@ add_executable(llama
     llama.cpp
     utils.h)
 
+if(NOT WIN32)
+    target_sources(llama PRIVATE tcp_server.cpp)
+endif()
+
 add_executable(quantize
     quantize.cpp
     utils.cpp

Makefile

@@ -191,11 +191,14 @@ utils.o: utils.cpp utils.h
 llama.o: llama.cpp llama.h
 	$(CXX) $(CXXFLAGS) -c llama.cpp -o llama.o
 
+tcp_server.o: tcp_server.cpp tcp_server.h
+	$(CXX) $(CXXFLAGS) -c tcp_server.cpp -o tcp_server.o
+
 clean:
 	rm -f *.o main quantize
 
-main: main.cpp ggml.o utils.o llama.o
+main: main.cpp ggml.o utils.o llama.o tcp_server.o
-	$(CXX) $(CXXFLAGS) main.cpp ggml.o utils.o llama.o -o main $(LDFLAGS)
+	$(CXX) $(CXXFLAGS) main.cpp ggml.o utils.o llama.o tcp_server.o -o main $(LDFLAGS)
 	./main -h
 
 quantize: quantize.cpp ggml.o utils.o

chat_tcp_client.sh

@@ -0,0 +1,45 @@
+#!/usr/bin/env bash
+
+PORT=${PORT:-8080}
+PROMPT="${PROMPT:-"Transcript of a dialog, where the User interacts with an Assistant named Bob. Bob is helpful, kind, honest, good at writing, and never fails to answer the User's requests immediately and with precision.
+
+User:Hello, Bob.
+Bob:Hello. How may I help you today?
+User:Please tell me the largest city in Europe.
+Bob:Sure. The largest city in Europe is Moscow, the capital of Russia.
+User:"}"
+RPROMPT="${RPROMPT:-"User:"}"
+N_PREDICT="${N_PREDICT:-"4096"}"
+REPEAT_PENALTY="${REPEAT_PENALTY:-"1.0"}"
+N_THREADS="${N_THREADS:-"4"}"
+
+# Open connection to the chat server
+exec 3<>/dev/tcp/127.0.0.1/${PORT}
+
+# Pass the arguments. The protocol is really simple:
+# 1. Pass the number of arguments followed by a linefeed
+# 2. Pass the arguments, with each being followed by "0"
+(
+echo -en "12\n"
+echo -en "-t\x00"
+echo -en "$N_THREADS\x00"
+echo -en "-n\x00"
+echo -en "$N_PREDICT\x00"
+echo -en "--repeat_penalty\x00"
+echo -en "$REPEAT_PENALTY\x00"
+echo -en "--color\x00"
+echo -en "-i\x00"
+echo -en "-r\x00"
+echo -en "$RPROMPT\x00"
+echo -en "-p\x00"
+echo -en "$PROMPT\x00"
+) >&3
+
+trap exit TERM
+
+# When we have passed the arguments, start printing socket data to the screen.
+# This is done in a background job because we also want to send data when
+# running in interactive mode.
+cat <&3 && echo "(disconnected, press \"enter\" twice to exit)" &
+cat >&3
+wait

chat_tcp_server.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+PORT=${PORT:-8080}
+MODEL=${MODEL:-models/7B/ggml-model-q4_0.bin}
+
+./main -l ${PORT} -m $MODEL

main.cpp

@@ -1,6 +1,7 @@
 #include "ggml.h"
 #include "utils.h"
 #include "llama.h"
+#include "tcp_server.h"
 
 #include <iostream>
 
@@ -65,5 +66,11 @@ int main(int argc, char ** argv) {
                 params.n_threads, std::thread::hardware_concurrency(), llama_print_system_info());
     }
 
+#ifndef _WIN32
+    if (params.listen_port != "") {
+      return listen_tcp(params, vocab, model, t_main_start_us, t_load_us);
+    }
+#endif
+
     return llama_main(params, vocab, model, t_main_start_us, t_load_us, std::cin, stdout, stderr);
 }

tcp_server.cpp

@@ -0,0 +1,245 @@
+#include "tcp_server.h"
+
+#include <iostream>
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+
+#include <signal.h>
+#include <unistd.h>
+#include <sys/wait.h>
+
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+
+class PosixStream : public std::istream {
+    public:
+        PosixStream(int fd) : std::istream(&buf), buf(fd) {}
+        ~PosixStream() { close(buf.get_fd()); }
+
+    private:
+        class PosixStreamBuf : public std::streambuf {
+            public:
+                PosixStreamBuf(int fd) : fd(fd) {}
+                int get_fd() const { return fd; }
+
+            protected:
+                virtual int_type underflow() {
+                    if (gptr() < egptr()) {
+                        return traits_type::to_int_type(*gptr());
+                    }
+
+                    ssize_t num_read = ::read(fd, buffer, BUFFER_SIZE);
+                    if (num_read <= 0) {
+                        return traits_type::eof();
+                    }
+
+                    setg(buffer, buffer, buffer + num_read);
+                    return traits_type::to_int_type(*gptr());
+                }
+
+            private:
+                static const int BUFFER_SIZE = 1024;
+                int fd;
+                char buffer[BUFFER_SIZE];
+        };
+
+        PosixStreamBuf buf;
+};
+
+void die(const char *msg, ...)
+{
+    va_list ap;
+
+    va_start(ap, msg);
+    vfprintf(stderr, msg, ap);
+    va_end(ap);
+    fputc('\n', stderr);
+    exit(1);
+}
+
+static char *read_argument(uint8_t **param_buf, size_t *param_buf_size, FILE *instream) {
+    bool done = false;
+    uint8_t *buf = *param_buf;
+    size_t bufsize = *param_buf_size;
+    size_t bufpos = 0;
+    while (!done) {
+        if (bufpos == bufsize) {
+            bufsize += 1024;
+            buf = (uint8_t *)realloc(buf, bufsize);
+            if (!buf) {
+                die("failed to allocate memory");
+            }
+        }
+
+        int c = fgetc(instream);
+        if (c == EOF) {
+            die("unexpected EOF client socket");
+        }
+        buf[bufpos++] = (uint8_t)c;
+        if (c == 0) {
+            // done reading argument
+            break;
+        }
+    }
+    *param_buf = buf;
+    *param_buf_size = bufsize;
+    return strdup((char *)buf);
+}
+
+static int read_arguments(int argc, char **argv, FILE *instream) {
+    int i = 1;
+    size_t param_buf_size = 0;
+    uint8_t *param_buf = nullptr;
+
+    for (i = 1; i < argc; i++) {
+        argv[i] = read_argument(&param_buf, &param_buf_size, instream);
+    }
+
+    free(param_buf);
+    return i;
+}
+
+static int serve_model(
+        gpt_params params,
+        gpt_vocab vocab,
+        llama_model model,
+        int64_t t_load_us,
+        int64_t t_main_start_us,
+        int sock_fd)
+{
+    char *response_data;
+    int argc;
+    char **argv;
+    FILE *instream = fdopen(sock_fd, "r");
+    FILE *outstream = fdopen(sock_fd, "w");
+    setvbuf(instream, NULL, _IONBF, 0);
+
+    // start by reading the parameter count
+    if (fscanf(instream, "%d\n", &argc) != 1) {
+        fprintf(outstream, "Error: First line must be character count\n");
+        fflush(outstream);
+        return 1;
+    }
+
+    argc += 1;  // add one extra argument to emulate the program command line
+    argv = (char **)malloc(argc * sizeof *argv);
+    argv[0] = nullptr;
+    if (read_arguments(argc, argv, instream) != argc) {
+        fprintf(outstream, "Error: Failed to read arguments\n");
+        fflush(outstream);
+    }
+
+    if (gpt_params_parse(argc, argv, params) == false) {
+        fprintf(outstream, "Error: Failed to parse parameters\n");
+        fflush(outstream);
+        return 1;
+    }
+
+    for (int i = 1; i < argc; i++) {
+        free(argv[i]);
+    }
+    free(argv);
+
+    PosixStream tcp_is(sock_fd);
+
+    return llama_main(params, vocab, model, t_load_us, t_main_start_us, tcp_is, outstream, outstream);
+}
+
+int listen_tcp(
+        gpt_params params,
+        gpt_vocab vocab,
+        llama_model model,
+        int64_t t_main_start_us,
+        int64_t t_load_us) {
+    int listen_fd;
+    int status;
+    pid_t child;
+    struct addrinfo hints;
+    struct addrinfo *servinfo, *p;
+    int yes = 1;
+
+    memset(&hints, 0, sizeof hints);
+    hints.ai_family = AF_INET;
+    hints.ai_socktype = SOCK_STREAM;
+    hints.ai_flags = AI_PASSIVE;
+
+    // This should only ever listen on a loopback address. Access from outside
+    // should be proxied via nginx or similar software
+    status = getaddrinfo("127.0.0.1", params.listen_port.c_str(), &hints, &servinfo);
+    if (status) {
+        die("getaddrinfo error: %s", gai_strerror(status));
+    }
+
+    // bind to the first addrinfo we can from the getaddrinfo results
+    for (p = servinfo; p != NULL; p = p->ai_next) {
+        listen_fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol);
+        if (listen_fd == -1) {
+            perror("server: socket");
+            continue;
+        }
+
+        if (setsockopt(listen_fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof yes)) {
+            die("setsockopt error: %s", params.listen_port.c_str(), strerror(errno));
+        }
+
+        if (bind(listen_fd, p->ai_addr, p->ai_addrlen) == 0) {
+            break;
+        }
+
+        close(listen_fd);
+        perror("server: bind");
+    }
+
+    freeaddrinfo(servinfo);
+
+    if (p == NULL) {
+        die("failed to bind: %s", strerror(errno));
+    }
+
+    if (listen(listen_fd, 20)) {
+        die("listen error: %s", strerror(errno));
+    }
+    // Don't track child processes, so ignore SIGCHLD to prevent zombies
+    signal(SIGCHLD, SIG_IGN);
+
+    for (;;) {
+        struct sockaddr_in client_addr = {0};
+        socklen_t client_addr_len = 0;
+
+        int sock_fd = accept(listen_fd,
+                (struct sockaddr *)&client_addr,
+                &client_addr_len);
+        if (sock_fd < 0) {
+            fprintf(stderr, "accept error: %s\n", strerror(errno));
+            break;
+        }
+
+        child = fork();
+        if (child == 0) {
+            // close the listen_fd since we won't use it in the child
+            close(listen_fd);
+            int ret = serve_model(params, vocab, model, t_main_start_us, t_load_us, sock_fd);
+            close(sock_fd);
+            return ret;
+        } else {
+            // close the client since we won't use it in the server
+            close(sock_fd);
+            sock_fd = 0;
+        }
+    }
+    close(listen_fd);
+
+    // ignore SIGTERM since we'll send it to the group
+    signal(SIGTERM, SIG_IGN);
+    // tell children to exit
+    kill(0, SIGTERM);
+    // wait for children to terminate
+    wait(&status);
+    return 0;
+}

tcp_server.h

@@ -0,0 +1,11 @@
+#pragma once
+
+#include "utils.h"
+#include "llama.h"
+
+int listen_tcp(
+    gpt_params params,
+    gpt_vocab vocab,
+    llama_model model,
+    int64_t t_main_start_us,
+    int64_t t_load_us);

utils.cpp

@@ -74,6 +74,10 @@ bool gpt_params_parse(int argc, char ** argv, gpt_params & params) {
             params.antiprompt.push_back(argv[++i]);
         } else if (arg == "--ignore-eos") {
             params.ignore_eos = true;
+#ifndef _WIN32
+        } else if (arg == "-l" || arg == "--listen") {
+            params.listen_port = argv[++i];
+#endif
         } else if (arg == "-h" || arg == "--help") {
             gpt_print_usage(argc, argv, params);
             exit(0);
@@ -119,6 +123,10 @@ void gpt_print_usage(int /*argc*/, char ** argv, const gpt_params & params) {
     fprintf(stderr, "  -b N, --batch_size N  batch size for prompt processing (default: %d)\n", params.n_batch);
     fprintf(stderr, "  -m FNAME, --model FNAME\n");
     fprintf(stderr, "                        model path (default: %s)\n", params.model.c_str());
+#ifndef _WIN32
+    fprintf(stderr, "  -l PORT, --listen PORT\n");
+    fprintf(stderr, "                        Run in TCP mode, listening on PORT\n");
+#endif
     fprintf(stderr, "\n");
 }
 

utils.h

@@ -40,6 +40,10 @@ struct gpt_params {
     std::vector<std::string> antiprompt; // string upon seeing which more user input is prompted
     bool instruct    = false; // instruction mode (used for Alpaca models)
     bool ignore_eos = false; // do not stop generating after eos
+
+#ifndef _WIN32
+    std::string listen_port = "";  // TCP port for when running in server mode
+#endif
 };
 
 bool gpt_params_parse(int argc, char ** argv, gpt_params & params);