consumerd: cleanup: use buffer view interface for mmap read subbuf

[lttng-tools.git] / src / common / kernel-consumer / kernel-consumer.c

diff --git a/src/common/kernel-consumer/kernel-consumer.c b/src/common/kernel-consumer/kernel-consumer.c
index 5075e05929238ade072391bf5367ae7f40c0433f..54314ec75a2c4d7758fd3c3ac2cd4d8492dee893 100644 (file)
--- a/src/common/kernel-consumer/kernel-consumer.c
+++ b/src/common/kernel-consumer/kernel-consumer.c
@@ -7,6 +7,8 @@
  *
  */
 
+#include "common/buffer-view.h"
+#include <stdint.h>
 #define _LGPL_SOURCE
 #include <assert.h>
 #include <poll.h>
@@ -113,6 +115,25 @@ int lttng_kconsumer_get_consumed_snapshot(struct lttng_consumer_stream *stream,
        return ret;
 }
 
+static
+int get_current_subbuf_addr(struct lttng_consumer_stream *stream,
+               const char **addr)
+{
+       int ret;
+       unsigned long mmap_offset;
+       const char *mmap_base = stream->mmap_base;
+
+       ret = kernctl_get_mmap_read_offset(stream->wait_fd, &mmap_offset);
+       if (ret < 0) {
+               PERROR("Failed to get mmap read offset");
+               goto error;
+       }
+
+       *addr = mmap_base + mmap_offset;
+error:
+       return ret;
+}
+
 /*
  * Take a snapshot of all the stream of a channel
  * RCU read-side lock must be held across this function to ensure existence of
@@ -228,9 +249,10 @@ static int lttng_kconsumer_snapshot_channel(
                while ((long) (consumed_pos - produced_pos) < 0) {
                        ssize_t read_len;
                        unsigned long len, padded_len;
+                       const char *subbuf_addr;
+                       struct lttng_buffer_view subbuf_view;
 
                        health_code_update();
-
                        DBG("Kernel consumer taking snapshot at pos %lu", consumed_pos);
 
                        ret = kernctl_get_subbuf(stream->wait_fd, &consumed_pos);
@@ -257,7 +279,15 @@ static int lttng_kconsumer_snapshot_channel(
                                goto error_put_subbuf;
                        }
 
-                       read_len = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, len,
+                       ret = get_current_subbuf_addr(stream, &subbuf_addr);
+                       if (ret) {
+                               goto error_put_subbuf;
+                       }
+
+                       subbuf_view = lttng_buffer_view_init(
+                                       subbuf_addr, 0, padded_len);
+                       read_len = lttng_consumer_on_read_subbuffer_mmap(ctx,
+                                       stream, &subbuf_view,
                                        padded_len - len, NULL);
                        /*
                         * We write the padded len in local tracefiles but the data len
@@ -1691,6 +1721,10 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                }
                break;
        case CONSUMER_CHANNEL_MMAP:
+       {
+               const char *subbuf_addr;
+               struct lttng_buffer_view subbuf_view;
+
                /* Get subbuffer size without padding */
                err = kernctl_get_subbuf_size(infd, &subbuf_size);
                if (err != 0) {
@@ -1710,18 +1744,25 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        goto error;
                }
 
+               ret = get_current_subbuf_addr(stream, &subbuf_addr);
+               if (ret) {
+                       goto error_put_subbuf;
+               }
+
                /* Make sure the tracer is not gone mad on us! */
                assert(len >= subbuf_size);
 
                padding = len - subbuf_size;
 
+               subbuf_view = lttng_buffer_view_init(subbuf_addr, 0, len);
+
                /* write the subbuffer to the tracefile */
-               ret = lttng_consumer_on_read_subbuffer_mmap(ctx, stream, subbuf_size,
-                               padding, &index);
+               ret = lttng_consumer_on_read_subbuffer_mmap(
+                               ctx, stream, &subbuf_view, padding, &index);
                /*
-                * The mmap operation should write subbuf_size amount of data when
-                * network streaming or the full padding (len) size when we are _not_
-                * streaming.
+                * The mmap operation should write subbuf_size amount of data
+                * when network streaming or the full padding (len) size when we
+                * are _not_ streaming.
                 */
                if ((ret != subbuf_size && stream->net_seq_idx != (uint64_t) -1ULL) ||
                                (ret != len && stream->net_seq_idx == (uint64_t) -1ULL)) {
@@ -1736,11 +1777,12 @@ ssize_t lttng_kconsumer_read_subbuffer(struct lttng_consumer_stream *stream,
                        write_index = 0;
                }
                break;
+       }
        default:
                ERR("Unknown output method");
                ret = -EPERM;
        }
-
+error_put_subbuf:
        err = kernctl_put_next_subbuf(infd);
        if (err != 0) {
                if (err == -EFAULT) {