[lttng-dev] [PATCH babeltrace v2] Introduce read_fit callback for format plugins
Simon Marchi
simon.marchi at polymtl.ca
Thu Oct 31 23:49:23 EDT 2013
The format plugins should implement this callback to tell whether they
are a good fit to read the given path or not. This allows to move
CTF-specific code from the core to ctf.c. This should be a step towards
having more than one input plugin.
The callback should return 1 if it wants to handle this path, 0 otherwise. It
should return -1 in case of catastrophic failure.
Signed-off-by: Simon Marchi <simon.marchi at polymtl.ca>
---
converter/babeltrace.c | 91 ++++++++++++++++++++++-----------------------
formats/ctf/ctf.c | 50 +++++++++++++++++++++++++
include/babeltrace/format.h | 1 +
3 files changed, 95 insertions(+), 47 deletions(-)
diff --git a/converter/babeltrace.c b/converter/babeltrace.c
index d5a7040..d1a8aa3 100644
--- a/converter/babeltrace.c
+++ b/converter/babeltrace.c
@@ -416,7 +416,16 @@ end:
return ret;
}
-static GPtrArray *traversed_paths = 0;
+/*
+ * Since nftw doesn't pass a user data pointer to its callbacks, we
+ * have to resort to global variables.
+ */
+struct traverse_trace_dir_args {
+ struct bt_format *format;
+ GPtrArray *paths;
+};
+
+static struct traverse_trace_dir_args traverse_trace_dir_args = {NULL, NULL};
/*
* traverse_trace_dir() is the callback function for File Tree Walk (nftw).
@@ -429,53 +438,32 @@ static GPtrArray *traversed_paths = 0;
static int traverse_trace_dir(const char *fpath, const struct stat *sb,
int tflag, struct FTW *ftwbuf)
{
- int dirfd, metafd;
- int closeret;
+ int ret;
+ struct traverse_trace_dir_args args = traverse_trace_dir_args;
- if (tflag != FTW_D)
- return 0;
+ assert(args.format != NULL);
+ assert(args.paths != NULL);
- dirfd = open(fpath, 0);
- if (dirfd < 0) {
- fprintf(stderr, "[error] [Context] Unable to open trace "
- "directory file descriptor.\n");
- return 0; /* partial error */
+ if (!args.format->read_fit) {
+ /* The plug-in needs to implement read_fit. */
+ return -1;
}
- metafd = openat(dirfd, "metadata", O_RDONLY);
- if (metafd < 0) {
- closeret = close(dirfd);
- if (closeret < 0) {
- perror("close");
- return -1;
- }
- /* No meta data, just return */
- return 0;
- } else {
- int err_close = 0;
- closeret = close(metafd);
- if (closeret < 0) {
- perror("close");
- err_close = 1;
- }
- closeret = close(dirfd);
- if (closeret < 0) {
- perror("close");
- err_close = 1;
- }
- if (err_close) {
- return -1;
- }
+ ret = args.format->read_fit(fpath, tflag == FTW_D);
- /* Add path to the global list */
- if (traversed_paths == NULL) {
- fprintf(stderr, "[error] [Context] Invalid open path array.\n");
- return -1;
- }
- g_ptr_array_add(traversed_paths, g_string_new(fpath));
+ /*
+ * If ret is negative (means error), we return directly. This will
+ * interrupt the file tree walk. If ret is 0, the format is not interested
+ * by the path, we also return directly.
+ */
+
+ if (ret > 0) {
+ /* Format is interested. Add path to the global list */
+ g_ptr_array_add(args.paths, g_string_new(fpath));
+ ret = 0;
}
- return 0;
+ return ret;
}
/*
@@ -499,15 +487,22 @@ int bt_context_add_traces_recursive(struct bt_context *ctx, const char *path,
/* Should lock traversed_paths mutex here if used in multithread */
- traversed_paths = g_ptr_array_new();
+ struct bt_format *format = bt_lookup_format(g_quark_from_string(format_str));
+ if (!format) {
+ ret = -1;
+ goto error;
+ }
+
+ traverse_trace_dir_args.paths = g_ptr_array_new();
+ traverse_trace_dir_args.format = format;
ret = nftw(path, traverse_trace_dir, 10, 0);
/* Process the array if ntfw did not return a fatal error */
if (ret >= 0) {
int i;
- for (i = 0; i < traversed_paths->len; i++) {
- GString *trace_path = g_ptr_array_index(traversed_paths,
+ for (i = 0; i < traverse_trace_dir_args.paths->len; i++) {
+ GString *trace_path = g_ptr_array_index(traverse_trace_dir_args.paths,
i);
int trace_id = bt_context_add_trace(ctx,
trace_path->str,
@@ -527,8 +522,8 @@ int bt_context_add_traces_recursive(struct bt_context *ctx, const char *path,
}
}
- g_ptr_array_free(traversed_paths, TRUE);
- traversed_paths = NULL;
+ g_ptr_array_free(traverse_trace_dir_args.paths, TRUE);
+ traverse_trace_dir_args.paths = NULL;
/* Should unlock traversed paths mutex here if used in multithread */
@@ -539,6 +534,8 @@ int bt_context_add_traces_recursive(struct bt_context *ctx, const char *path,
fprintf(stderr, "[error] Cannot open any trace for reading.\n\n");
ret = -ENOENT; /* failure */
}
+
+error:
return ret;
}
@@ -697,7 +694,7 @@ int main(int argc, char **argv)
}
}
fmt_read = bt_lookup_format(g_quark_from_static_string(opt_input_format));
- if (!fmt_read || fmt_read->name != g_quark_from_static_string("ctf")) {
+ if (!fmt_read) {
fprintf(stderr, "[error] Format \"%s\" is not supported.\n\n",
opt_input_format);
partial_error = 1;
diff --git a/formats/ctf/ctf.c b/formats/ctf/ctf.c
index 5fcfcdd..101eafb 100644
--- a/formats/ctf/ctf.c
+++ b/formats/ctf/ctf.c
@@ -111,6 +111,9 @@ static
int ctf_convert_index_timestamp(struct bt_trace_descriptor *tdp);
static
+int ctf_read_fit(const char *fpath, int is_dir);
+
+static
rw_dispatch read_dispatch_table[] = {
[ CTF_TYPE_INTEGER ] = ctf_integer_read,
[ CTF_TYPE_FLOAT ] = ctf_float_read,
@@ -144,6 +147,7 @@ struct bt_format ctf_format = {
.timestamp_begin = ctf_timestamp_begin,
.timestamp_end = ctf_timestamp_end,
.convert_index_timestamp = ctf_convert_index_timestamp,
+ .read_fit = ctf_read_fit,
};
static
@@ -2095,6 +2099,52 @@ int ctf_convert_index_timestamp(struct bt_trace_descriptor *tdp)
}
static
+int ctf_read_fit(const char *fpath, int is_dir)
+{
+ int dirfd, metafd;
+ int closeret;
+
+ if (!is_dir)
+ return 0;
+
+ dirfd = open(fpath, 0);
+ if (dirfd < 0) {
+ fprintf(stderr, "[error] [Context] Unable to open trace "
+ "directory file descriptor.\n");
+ return 0; /* partial error */
+ }
+ metafd = openat(dirfd, "metadata", O_RDONLY);
+ if (metafd < 0) {
+ closeret = close(dirfd);
+ if (closeret < 0) {
+ perror("close");
+ return -1;
+ }
+ /* No meta data, just return */
+ return 0;
+ } else {
+ int err_close = 0;
+
+ closeret = close(metafd);
+ if (closeret < 0) {
+ perror("close");
+ err_close = 1;
+ }
+ closeret = close(dirfd);
+ if (closeret < 0) {
+ perror("close");
+ err_close = 1;
+ }
+ if (err_close) {
+ return -1;
+ }
+ }
+
+ /* This path is interesting. */
+ return 1;
+}
+
+static
int ctf_close_file_stream(struct ctf_file_stream *file_stream)
{
int ret;
diff --git a/include/babeltrace/format.h b/include/babeltrace/format.h
index 07e854f..588c0ff 100644
--- a/include/babeltrace/format.h
+++ b/include/babeltrace/format.h
@@ -77,6 +77,7 @@ struct bt_format {
uint64_t (*timestamp_end)(struct bt_trace_descriptor *descriptor,
struct bt_trace_handle *handle, enum bt_clock_type type);
int (*convert_index_timestamp)(struct bt_trace_descriptor *descriptor);
+ int (*read_fit)(const char *path, int is_dir);
};
extern struct bt_format *bt_lookup_format(bt_intern_str qname);
--
1.8.3.2
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