#define _I3_SHMLOG_H
#include <stdint.h>
+#include <pthread.h>
+/*
+ * Header of the shmlog file. Used by i3/src/log.c and i3/i3-dump-log/main.c.
+ *
+ */
typedef struct i3_shmlog_header {
+ /* Byte offset where the next line will be written to. */
uint32_t offset_next_write;
+
+ /* Byte offset where the last wrap occured. */
uint32_t offset_last_wrap;
+
+ /* The size of the logfile in bytes. Since the size is limited to 25 MiB
+ * an uint32_t is sufficient. */
uint32_t size;
+
+ /* wrap counter. We need it to reliably signal to clients that we just
+ * wrapped (clients cannot use offset_last_wrap because that might
+ * coincidentally be exactly the same as previously). Overflows can happen
+ * and don’t matter — clients use an equality check (==). */
+ uint32_t wrap_count;
+
+ /* pthread condvar which will be broadcasted whenever there is a new
+ * message in the log. i3-dump-log uses this to implement -f (follow, like
+ * tail -f) in an efficient way. */
+ pthread_cond_t condvar;
} i3_shmlog_header;
#endif