--- /dev/null
+/*
+ * Copyright (C) 2011 - Julien Desfossez <julien.desfossez@polymtl.ca>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; only version 2
+ * of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _LTTNG_KCONSUMERD_H
+#define _LTTNG_KCONSUMERD_H
+
+#include <limits.h>
+#include <lttng/lttng.h>
+
+/*
+ * When the receiving thread dies, we need to have a way to make the polling
+ * thread exit eventually. If all FDs hang up (normal case when the
+ * ltt-sessiond stops), we can exit cleanly, but if there is a problem and for
+ * whatever reason some FDs remain open, the consumer should still exit
+ * eventually.
+ *
+ * If the timeout is reached, it means that during this period no events
+ * occurred on the FDs so we need to force an exit. This case should not happen
+ * but it is a safety to ensure we won't block the consumer indefinitely.
+ *
+ * The value of 2 seconds is an arbitrary choice.
+ */
+#define LTTNG_KCONSUMERD_POLL_GRACE_PERIOD 2000
+
+/* Commands for kconsumerd */
+enum lttng_kconsumerd_command {
+ ADD_STREAM,
+ UPDATE_STREAM, /* pause, delete, active depending on fd state */
+ STOP, /* inform the kconsumerd to quit when all fd has hang up */
+};
+
+/* State of each fd in consumerd */
+enum lttng_kconsumerd_fd_state {
+ ACTIVE_FD,
+ PAUSE_FD,
+ DELETE_FD,
+};
+
+struct lttng_kconsumerd_fd_list {
+ struct cds_list_head head;
+};
+
+/*
+ * Internal representation of the FDs, sessiond_fd is used to identify uniquely
+ * a fd
+ */
+struct lttng_kconsumerd_fd {
+ struct cds_list_head list;
+ int sessiond_fd; /* used to identify uniquely a fd with sessiond */
+ int consumerd_fd; /* fd to consume */
+ int out_fd; /* output file to write the data */
+ off_t out_fd_offset; /* write position in the output file descriptor */
+ char path_name[PATH_MAX]; /* tracefile name */
+ enum lttng_kconsumerd_fd_state state;
+ unsigned long max_sb_size; /* the subbuffer size for this channel */
+ void *mmap_base;
+ size_t mmap_len;
+ enum lttng_event_output output; /* splice or mmap */
+};
+
+/*
+ * Kernel consumer local data to the program.
+ */
+struct lttng_kconsumerd_local_data {
+ /* function to call when data is available on a buffer */
+ int (*on_buffer_ready)(struct lttng_kconsumerd_fd *kconsumerd_fd);
+ /* socket to communicate errors with sessiond */
+ int kconsumerd_error_socket;
+ /* socket to exchange commands with sessiond */
+ char *kconsumerd_command_sock_path;
+ /* communication with splice */
+ int kconsumerd_thread_pipe[2];
+ /* pipe to wake the poll thread when necessary */
+ int kconsumerd_poll_pipe[2];
+ /* to let the signal handler wake up the fd receiver thread */
+ int kconsumerd_should_quit[2];
+};
+
+/*
+ * Initialise the necessary environnement:
+ * - create a new context
+ * - create the poll_pipe
+ * - create the should_quit pipe (for signal handler)
+ * - create the thread pipe (for splice)
+ *
+ * Takes a function pointer as argument, this function is called when data is
+ * available on a buffer. This function is responsible to do the
+ * kernctl_get_next_subbuf, read the data with mmap or splice depending on the
+ * buffer configuration and then kernctl_put_next_subbuf at the end.
+ *
+ * Returns a pointer to the new context or NULL on error.
+ */
+extern struct lttng_kconsumerd_local_data *lttng_kconsumerd_create(
+ int (*buffer_ready)(struct lttng_kconsumerd_fd *kconsumerd_fd));
+
+/*
+ * Close all fds associated with the instance and free the context.
+ */
+extern void lttng_kconsumerd_destroy(struct lttng_kconsumerd_local_data *ctx);
+
+/*
+ * Mmap the ring buffer, read it and write the data to the tracefile.
+ *
+ * Returns the number of bytes written.
+ */
+extern int lttng_kconsumerd_on_read_subbuffer_mmap(
+ struct lttng_kconsumerd_local_data *ctx,
+ struct lttng_kconsumerd_fd *kconsumerd_fd, unsigned long len);
+
+/*
+ * Splice the data from the ring buffer to the tracefile.
+ *
+ * Returns the number of bytes spliced.
+ */
+extern int lttng_kconsumerd_on_read_subbuffer_splice(
+ struct lttng_kconsumerd_local_data *ctx,
+ struct lttng_kconsumerd_fd *kconsumerd_fd, unsigned long len);
+
+/*
+ * Send return code to session daemon.
+ *
+ * Returns the return code of sendmsg : the number of bytes transmitted or -1
+ * on error.
+ */
+extern int lttng_kconsumerd_send_error(
+ struct lttng_kconsumerd_local_data *ctx, int cmd);
+
+/*
+ * Poll on the should_quit pipe and the command socket return -1 on error and
+ * should exit, 0 if data is available on the command socket.
+ */
+extern int lttng_kconsumerd_poll_socket(struct pollfd *kconsumerd_sockpoll);
+
+/*
+ * This thread polls the fds in the ltt_fd_list to consume the data and write
+ * it to tracefile if necessary.
+ */
+extern void *lttng_kconsumerd_thread_poll_fds(void *data);
+
+/*
+ * This thread listens on the consumerd socket and receives the file
+ * descriptors from ltt-sessiond.
+ */
+extern void *lttng_kconsumerd_thread_receive_fds(void *data);
+
+/*
+ * Called from signal handler to ensure a clean exit.
+ */
+extern void lttng_kconsumerd_should_exit(
+ struct lttng_kconsumerd_local_data *ctx);
+
+/*
+ * Cleanup the daemon's socket on exit.
+ */
+extern void lttng_kconsumerd_cleanup(void);
+
+/*
+ * Set the error socket for communication with a session daemon.
+ */
+extern void lttng_kconsumerd_set_error_sock(
+ struct lttng_kconsumerd_local_data *ctx, int sock);
+
+/*
+ * Set the command socket path for communication with a session daemon.
+ */
+extern void lttng_kconsumerd_set_command_sock_path(
+ struct lttng_kconsumerd_local_data *ctx, char *sock);
+
+#endif /* _LTTNG_KCONSUMERD_H */
projects / lttng-tools.git / blobdiff