Add tracecmd_set_cpu_to_timestamp()

This adds an API to set the CPU data field to the location
specified by a timestamp. It looks for the page that contains or
is before the timestamp to allow for walking forward to find
the specified event.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

3 files changed, 140 insertions, 9 deletions

diff --git a/trace-cmd.h b/trace-cmd.h
index 39dff16..cc63627 100644
--- a/trace-cmd.h
+++ b/trace-cmd.h
@@ -59,6 +59,9 @@ struct record *
 tracecmd_translate_data(struct tracecmd_input *handle,
                         void *ptr, int size);
 
+int tracecmd_set_cpu_to_timestamp(struct tracecmd_input *handle,
+                                  int cpu, unsigned long long ts);
+
 int tracecmd_ftrace_overrides(struct tracecmd_input *handle);
 struct pevent *tracecmd_get_pevent(struct tracecmd_input *handle);
 
diff --git a/trace-input.c b/trace-input.c
index 0a8ebb1..0d50bf0 100644
--- a/trace-input.c
+++ b/trace-input.c
@@ -537,8 +537,10 @@ static int get_read_page(struct tracecmd_input *handle, int cpu,
         /* reset the file pointer back */
         lseek64(handle->fd, save_seek, SEEK_SET);
 
-        return 0;
+        handle->cpu_data[cpu].timestamp =
+                data2host8(handle->pevent, handle->cpu_data[cpu].page);
 
+        return 0;
 }
 
 static int get_page(struct tracecmd_input *handle, int cpu,
@@ -568,6 +570,9 @@ static int get_page(struct tracecmd_input *handle, int cpu,
         if (handle->cpu_data[cpu].page == MAP_FAILED)
                 return -1;
 
+        handle->cpu_data[cpu].timestamp =
+                data2host8(handle->pevent, handle->cpu_data[cpu].page);
+
         return 0;
 }
 static int get_next_page(struct tracecmd_input *handle, int cpu)
@@ -758,6 +763,72 @@ tracecmd_read_at(struct tracecmd_input *handle, unsigned long long offset,
                 return find_and_read_event(handle, offset, pcpu);
 }
 
+int
+tracecmd_set_cpu_to_timestamp(struct tracecmd_input *handle, int cpu,
+                              unsigned long long ts)
+{
+        struct cpu_data *cpu_data = &handle->cpu_data[cpu];
+        off64_t start, end, next;
+
+        if (cpu < 0 || cpu >= handle->cpus) {
+                errno = -EINVAL;
+                return -1;
+        }
+
+        if (!cpu_data->page) {
+                if (init_cpu(handle, cpu))
+                    return -1;
+        }
+
+        if (cpu_data->timestamp == ts)
+                return 0;
+
+        if (cpu_data->timestamp < ts) {
+                start = cpu_data->offset;
+                end = cpu_data->file_offset + cpu_data->file_size;
+                if (end & (handle->page_size - 1))
+                        end &= ~(handle->page_size - 1);
+                else
+                        end -= handle->page_size;
+                next = end;
+        } else {
+                end = cpu_data->offset;
+                start = cpu_data->file_offset;
+                next = start;
+        }
+
+        while (start < end) {
+                if (get_page(handle, cpu, next))
+                        return -1;
+
+                if (cpu_data->timestamp == ts)
+                        break;
+
+                if (cpu_data->timestamp < ts)
+                        start = next;
+                else
+                        end = next;
+
+                next = start + (end - start) / 2;
+                next &= ~(handle->page_size - 1);
+        }
+
+        /*
+         * We need to end up on a page before the time stamp.
+         * We go back even if the timestamp is the same. This is because
+         * we want the event with the timestamp, not the page. The page
+         * can start with the timestamp we are looking for, but the event
+         * may be on the previous page.
+         */
+        if (cpu_data->timestamp >= ts &&
+            cpu_data->offset > cpu_data->file_offset)
+                get_page(handle, cpu, cpu_data->offset - handle->page_size);
+
+        cpu_data->index = 0;
+
+        return 0;
+}
+
 static unsigned int
 translate_data(struct tracecmd_input *handle,
                void **ptr, unsigned long long *delta, int *length)
@@ -976,6 +1047,9 @@ static int init_read(struct tracecmd_input *handle, int cpu)
         /* reset the file pointer back */
         lseek64(handle->fd, save_seek, SEEK_SET);
 
+        handle->cpu_data[cpu].timestamp =
+                data2host8(handle->pevent, handle->cpu_data[cpu].page);
+
         return 0;
 }
 
@@ -1004,6 +1078,8 @@ static int init_cpu(struct tracecmd_input *handle, int cpu)
 
                 return init_read(handle, cpu);
         }
+        handle->cpu_data[cpu].timestamp =
+                data2host8(handle->pevent, handle->cpu_data[cpu].page);
         return 0;
 }
 
diff --git a/trace-read.c b/trace-read.c
index bf01c55..48c9510 100644
--- a/trace-read.c
+++ b/trace-read.c
@@ -47,10 +47,11 @@ static int filter_cpu = -1;
 /* Debug variables for testing tracecmd_read_at */
 #define TEST_READ_AT 0
 #if TEST_READ_AT
+#define DO_TEST
 static off64_t test_read_at_offset;
 static int test_read_at_copy = 100;
 static int test_read_at_index;
-static void test_read_at(struct tracecmd_input *handle)
+static void show_test(struct tracecmd_input *handle)
 {
         struct pevent *pevent;
         struct record *record;
@@ -74,21 +75,72 @@ static void test_read_at(struct tracecmd_input *handle)
         free(record);
 }
 
-static void test_read_at_save(struct record *record)
+static void test_save(struct record *record, int cpu)
 {
         if (test_read_at_index++ == test_read_at_copy) {
                 test_read_at_offset = record->offset;
                 printf("\nUSING THIS RECORD\n");
         }
 }
-#else
-static void test_read_at(struct tracecmd_input *handle)
+#endif /* TEST_READ_AT */
+
+/* Debug variables for testing tracecmd_set_cpu_at_timestamp */
+#define TEST_AT_TIMESTAMP 0
+#if TEST_AT_TIMESTAMP
+#define DO_TEST
+static unsigned long long test_at_timestamp_ts;
+static int test_at_timestamp_copy = 100;
+static int test_at_timestamp_cpu = -1;
+static int test_at_timestamp_index;
+static void show_test(struct tracecmd_input *handle)
 {
+        struct pevent *pevent;
+        struct record *record;
+        struct trace_seq s;
+        int cpu = test_at_timestamp_cpu;
+
+        if (!test_at_timestamp_ts) {
+                printf("\nNO RECORD COPIED\n");
+                return;
+        }
+
+        pevent = tracecmd_get_pevent(handle);
+
+        if (tracecmd_set_cpu_to_timestamp(handle, cpu, test_at_timestamp_ts))
+                return;
+
+        record = tracecmd_read_data(handle, cpu);
+        printf("\nHERE'S THE COPY RECORD with page %p offset=%p\n",
+               (void *)(record->offset & ~(page_size - 1)),
+               (void *)record->offset);
+        trace_seq_init(&s);
+        pevent_print_event(pevent, &s, cpu, record->data, record->size, record->ts);
+        trace_seq_do_printf(&s);
+        printf("\n");
+
+        free(record);
+}
+
+static void test_save(struct record *record, int cpu)
+{
+        if (test_at_timestamp_index++ == test_at_timestamp_copy) {
+                test_at_timestamp_ts = record->ts;
+                test_at_timestamp_cpu = cpu;
+                printf("\nUSING THIS RECORD page=%p offset=%p\n",
+                       (void *)(record->offset & ~(page_size - 1)),
+                       (void *)record->offset);
+        }
 }
-static void test_read_at_save(struct record *record)
+#endif /* TEST_AT_TIMESTAMP */
+
+#ifndef DO_TEST
+static void show_test(struct tracecmd_input *handle)
 {
 }
-#endif /* TEST_READ_AT */
+static void test_save(struct record *record, int cpu)
+{
+}
+#endif
 
 static void show_data(struct tracecmd_input *handle, int cpu)
 {
@@ -100,7 +152,7 @@ static void show_data(struct tracecmd_input *handle, int cpu)
 
         record = tracecmd_read_data(handle, cpu);
 
-        test_read_at_save(record);
+        test_save(record, cpu);
 
         trace_seq_init(&s);
         pevent_print_event(pevent, &s, cpu, record->data, record->size, record->ts);
@@ -168,7 +220,7 @@ static void read_data_info(struct tracecmd_input *handle)
 
         } while (next >= 0);
 
-        test_read_at(handle);
+        show_test(handle);
 }
 
 struct tracecmd_input *read_trace_header(void)