#include "config.h"
/**
- * io - simple library for stateful io handling.
+ * io - simple library for asynchronous io handling.
*
- * io provides a simple mechanism to write I/O servers with multiple
- * connections. Handling of connections is multiplexed, and function
- * indicate what they want written or read, and what follow-on
- * function to call on success (or failure).
+ * io provides a mechanism to write I/O servers with multiple
+ * connections. Each callback indicates what I/O they plan next
+ * (eg. read, write). It is also possible to write custom I/O
+ * plans.
+ *
+ * When compiled with DEBUG, control flow is changed so that rather
+ * than returning to the main io_loop(), plans are executed sequentially
+ * providing a backtrace showing what has occurred on that connection.
+ * Which connection(s) do this depends on the user-specified io_debug
+ * function.
*
* Example:
* // Given tr A-Z a-z outputs tr a-z a-z
* #include <signal.h>
* #include <sys/types.h>
* #include <sys/wait.h>
+ * #include <string.h>
*
* struct buffer {
- * size_t max, off, rlen;
- * char *buf;
- * };
- *
- * struct stdin_buffer {
- * struct io_conn *reader, *writer;
- * size_t len;
- * char inbuf[4096];
+ * bool finished;
+ * size_t start, end, rlen, wlen;
+ * char buf[4096];
* };
*
- * // This reads from stdin.
- * static struct io_plan *wake_writer(struct io_conn *, struct stdin_buffer *);
- * // This writes the stdin buffer to the child.
- * static struct io_plan *write_to_child(struct io_conn *c,
- * struct stdin_buffer *b);
- * static struct io_plan *read_stdin(struct io_conn *c, struct stdin_buffer *b)
+ * static void finish(struct io_conn *c, struct buffer *b)
* {
- * assert(c == b->reader);
- * b->len = sizeof(b->inbuf);
- * return io_read_partial(b->inbuf, &b->len,
- * io_next(c, wake_writer, b));
+ * // Mark us finished.
+ * b->finished = true;
+ * // Wake writer just in case it's asleep.
+ * io_wake(b);
* }
*
- * static struct io_plan *wake_writer(struct io_conn *c, struct stdin_buffer *b)
+ * static struct io_plan read_in(struct io_conn *c, struct buffer *b)
* {
- * assert(c == b->reader);
- * io_wake(b->writer, write_to_child, b);
- * return io_idle(c);
- * }
+ * // Add what we just read.
+ * b->end += b->rlen;
+ * assert(b->end <= sizeof(b->buf));
*
- * static void reader_exit(struct io_conn *c, struct stdin_buffer *b)
- * {
- * assert(c == b->reader);
- * io_wake(b->writer, write_to_child, b);
- * b->reader = NULL;
- * }
+ * // If we just read something, wake writer.
+ * if (b->rlen != 0)
+ * io_wake(b);
*
- * static struct io_plan *wake_reader(struct io_conn *c, struct stdin_buffer *b)
- * {
- * assert(c == b->writer);
- * io_wake(b->reader, read_stdin, b);
- * return io_idle(c);
- * }
+ * // If buffer is empty, return to start.
+ * if (b->start == b->end)
+ * b->start = b->end = 0;
*
- * static struct io_plan *write_to_child(struct io_conn *conn,
- * struct stdin_buffer *b)
- * {
- * assert(conn == b->writer);
- * if (!b->reader)
- * return io_close(conn, NULL);
- * return io_write(b->inbuf, b->len, io_next(conn, wake_reader, b));
- * }
+ * // Read in some of the rest.
+ * b->rlen = sizeof(b->buf) - b->end;
*
- * static struct io_plan *start_writer(struct io_conn *conn,
- * struct stdin_buffer *b)
- * {
- * assert(conn == b->writer);
- * return io_idle(conn);
- * }
+ * // No room? Wait for writer
+ * if (b->rlen == 0)
+ * return io_wait(b, read_in, b);
*
- * static void fail_child_write(struct io_conn *conn, struct stdin_buffer *b)
- * {
- * if (b->reader)
- * err(1, "Failed writing to child.");
+ * return io_read_partial(b->buf + b->end, &b->rlen, read_in, b);
* }
*
- * // This reads from the child and saves it into buffer.
- * static struct io_plan *read_from_child(struct io_conn *conn,
- * struct buffer *b)
+ * static struct io_plan write_out(struct io_conn *c, struct buffer *b)
* {
- * b->off += b->rlen;
- *
- * if (b->off == b->max) {
- * if (b->max == 0)
- * b->max = 128;
- * else if (b->max >= 1024*1024)
- * b->max += 1024*1024;
- * else
- * b->max *= 2;
- * b->buf = realloc(b->buf, b->max);
+ * // Remove what we just wrote.
+ * b->start += b->wlen;
+ * assert(b->start <= sizeof(b->buf));
+ *
+ * // If we wrote somthing, wake writer.
+ * if (b->wlen != 0)
+ * io_wake(b);
+ *
+ * b->wlen = b->end - b->start;
+ * // Nothing to write? Wait for reader.
+ * if (b->wlen == 0) {
+ * if (b->finished)
+ * return io_close();
+ * return io_wait(b, write_out, b);
* }
*
- * b->rlen = b->max - b->off;
- * return io_read_partial(b->buf + b->off, &b->rlen,
- * io_next(conn, read_from_child, b));
+ * return io_write_partial(b->buf + b->start, &b->wlen, write_out, b);
* }
*
* // Feed a program our stdin, gather its stdout, print that at end.
* int main(int argc, char *argv[])
* {
* int tochild[2], fromchild[2];
- * struct buffer out = { 0, 0, 0, NULL };
- * struct stdin_buffer sbuf;
+ * struct buffer to, from;
* int status;
- * size_t off;
- * ssize_t ret;
+ * struct io_conn *reader;
*
* if (argc == 1)
* errx(1, "Usage: runner <cmdline>...");
* close(fromchild[1]);
* signal(SIGPIPE, SIG_IGN);
*
- * sbuf.reader = io_new_conn(STDIN_FILENO, read_stdin, reader_exit, &sbuf);
- * sbuf.writer = io_new_conn(tochild[1], start_writer, fail_child_write,
- * &sbuf);
- * if (!sbuf.reader || !sbuf.writer
- * || !io_new_conn(fromchild[0], read_from_child, NULL, &out))
- * err(1, "Allocating connections");
+ * // Read from stdin, write to child.
+ * memset(&to, 0, sizeof(to));
+ * reader = io_new_conn(STDIN_FILENO, read_in(NULL, &to));
+ * io_set_finish(reader, finish, &to);
+ * io_new_conn(tochild[1], write_out(NULL, &to));
+ *
+ * // Read from child, write to stdout.
+ * reader = io_new_conn(fromchild[0], read_in(NULL, &from));
+ * io_set_finish(reader, finish, &from);
+ * io_new_conn(STDOUT_FILENO, write_out(NULL, &from));
*
* io_loop();
* wait(&status);
*
- * for (off = 0; off < out.off; off += ret) {
- * ret = write(STDOUT_FILENO, out.buf+off, out.off-off);
- * if (ret < 0)
- * err(1, "Writing stdout");
- * }
- * free(out.buf);
- *
* return WIFEXITED(status) ? WEXITSTATUS(status) : 2;
* }
*
return 1;
if (strcmp(argv[1], "depends") == 0) {
+ printf("ccan/typesafe_cb\n");
printf("ccan/time\n");
printf("ccan/timer\n");
return 0;
projects / ccan / blobdiff