Previously it was necessary to count the number of pollfds contained
in a linked list. This change introduces the optimisation of storing a
running total of the number of pollfds.
---
libusb/io.c | 16 ++++++++--------
libusb/libusbi.h | 1 +
2 files changed, 9 insertions(+), 8 deletions(-)
diff --git a/libusb/io.c b/libusb/io.c
index 314184f..d6eb3b5 100644
--- a/libusb/io.c
+++ b/libusb/io.c
@@ -1060,6 +1060,7 @@ int usbi_io_init(struct libusb_context *ctx)
usbi_cond_init(&ctx->event_waiters_cond, NULL);
list_init(&ctx->flying_transfers);
list_init(&ctx->pollfds);
+ ctx->pollfds_cnt = 0;
/* FIXME should use an eventfd on kernels that support it */
r = usbi_pipe(ctx->ctrl_pipe);
@@ -1893,8 +1894,7 @@ static int handle_events(struct libusb_context *ctx,
struct timeval *tv)
int timeout_ms;
usbi_mutex_lock(&ctx->pollfds_lock);
- list_for_each_entry(ipollfd, &ctx->pollfds, list, struct usbi_pollfd)
- nfds++;
+ nfds = ctx->pollfds_cnt;
/* TODO: malloc when number of fd's changes, not on every poll */
if (nfds != 0)
@@ -2421,6 +2421,7 @@ int usbi_add_pollfd(struct libusb_context *ctx,
libusb_event_handle handle, shor
ipollfd->pollfd.direction = poll_events_to_event_dirs(events);
usbi_mutex_lock(&ctx->pollfds_lock);
list_add_tail(&ipollfd->list, &ctx->pollfds);
+ ++ctx->pollfds_cnt;
usbi_mutex_unlock(&ctx->pollfds_lock);
#ifdef LIBUSB_EVENT_HANDLE_IS_FD
@@ -2453,6 +2454,7 @@ void usbi_remove_pollfd(struct libusb_context *ctx,
libusb_event_handle handle)
}
list_del(&ipollfd->list);
+ --ctx->pollfds_cnt;
usbi_mutex_unlock(&ctx->pollfds_lock);
free(ipollfd);
#ifdef LIBUSB_EVENT_HANDLE_IS_FD
@@ -2492,9 +2494,8 @@ const struct libusb_pollfd ** LIBUSB_CALL
libusb_get_pollfds(
USBI_GET_CONTEXT(ctx);
usbi_mutex_lock(&ctx->pollfds_lock);
- list_for_each_entry(ipollfd, &ctx->pollfds, list, struct usbi_pollfd)
- cnt++;
-
+ cnt = ctx->pollfds_cnt;
+
/* Allocate enough space for the pointers and the libusb_event
* structures after the last pointer. */
alloc_size = ((cnt + 1) * sizeof(struct libusb_pollfd *)) +
@@ -2553,9 +2554,8 @@ struct libusb_event ** LIBUSB_CALL libusb_get_events(
USBI_GET_CONTEXT(ctx);
usbi_mutex_lock(&ctx->pollfds_lock);
- list_for_each_entry(ipollfd, &ctx->pollfds, list, struct usbi_pollfd)
- cnt++;
-
+ cnt = ctx->pollfds_cnt;
+
/* Allocate enough space for the pointers and the libusb_event
* structures after the last pointer. */
alloc_size = ((cnt + 1) * sizeof(struct libusb_event *)) +
diff --git a/libusb/libusbi.h b/libusb/libusbi.h
index 7c4f1f1..52d39ff 100644
--- a/libusb/libusbi.h
+++ b/libusb/libusbi.h
@@ -247,6 +247,7 @@ struct libusb_context {
/* list of poll fds */
struct list_head pollfds;
+ size_t pollfds_cnt;
usbi_mutex_t pollfds_lock;
/* a counter that is set when we want to interrupt event handling, in
order
--
1.7.9.5
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