lander/include/event_loop.h

#ifndef LANDER_EVENT_LOOP
#define LANDER_EVENT_LOOP

#include <stdbool.h>
#include <stdint.h>
#include <stdlib.h>

// Size of the read and write buffers for each connection, in bytes
#define EVENT_LOOP_BUFFER_SIZE 1024

/**
 * Represents an active connection managed by the event loop
 */
typedef enum {
  event_loop_conn_state_req = 0,
  event_loop_conn_state_res = 1,
  event_loop_conn_state_end = 2,
} event_loop_conn_state;

typedef struct event_loop_conn {
  int fd;
  event_loop_conn_state state;
  // buffer for reading
  size_t rbuf_size;
  size_t rbuf_read;
  uint8_t rbuf[EVENT_LOOP_BUFFER_SIZE];
  // buffer for writing
  size_t wbuf_size;
  size_t wbuf_sent;
  uint8_t wbuf[EVENT_LOOP_BUFFER_SIZE];

  // If true, the server will close the connection after the final write buffer
  // has been written
  bool close_after_write;
  void *ctx;
} event_loop_conn;

/*
 * Main struct object representing the event loop
 */
typedef struct event_loop {
  event_loop_conn **connections;
  size_t connection_count;
  // Global context passed to every connection
  void *gctx;
  // Function to initialize a context for a connection
  void *(*ctx_init)(void *gctx);
  // Function to free a context for a connection
  void (*ctx_free)(void *ctx);
  bool (*handle_data)(event_loop_conn *conn);
} event_loop;

/*
 * Initialize a new event_loop_conn struct
 */
event_loop_conn *event_loop_conn_init(event_loop *el);

void event_loop_conn_free(event_loop *el, event_loop_conn *conn);

/*
 * Process data on a connection
 */
void event_loop_conn_io(event_loop *el, event_loop_conn *conn);

/*
 * Initialize a new event_loop struct
 */
event_loop *event_loop_init();

/*
 * Place a new connection into the event loop's internal array.
 *
 * Returns -1 if the internal realloc failed
 */
int event_loop_put(event_loop *el, event_loop_conn *conn);

/**
 * Accept a new connection for the given file descriptor.
 */
int event_loop_accept(event_loop *el, int fd);

/*
 * Run the event loop. This function never returns.
 */
void event_loop_run(event_loop *el, int port);

#endif