Add a logging facility.

This sets up a hierarchical logging facility, so that we can add logging
statements liberally, and turn them on in a fine-grained manner.

1 files changed, 78 insertions, 0 deletions

diff --git a/src/log.c b/src/log.c
new file mode 100644
index 00000000..022dc584
--- /dev/null
+++ b/src/log.c
@@ -0,0 +1,78 @@
+#include "jemalloc/internal/jemalloc_preamble.h"
+#include "jemalloc/internal/jemalloc_internal_includes.h"
+
+#include "jemalloc/internal/log.h"
+
+char log_var_names[JEMALLOC_LOG_BUFSIZE];
+atomic_b_t log_init_done = ATOMIC_INIT(false);
+
+/*
+ * Returns true if we were able to pick out a segment.  Fills in r_segment_end
+ * with a pointer to the first character after the end of the string.
+ */
+static const char *
+log_var_extract_segment(const char* segment_begin) {
+	const char *end;
+	for (end = segment_begin; *end != '\0' && *end != '|'; end++) {
+	}
+	return end;
+}
+
+static bool
+log_var_matches_segment(const char *segment_begin, const char *segment_end,
+    const char *log_var_begin, const char *log_var_end) {
+	assert(segment_begin <= segment_end);
+	assert(log_var_begin < log_var_end);
+
+	ptrdiff_t segment_len = segment_end - segment_begin;
+	ptrdiff_t log_var_len = log_var_end - log_var_begin;
+	/* The special '.' segment matches everything. */
+	if (segment_len == 1 && *segment_begin == '.') {
+		return true;
+	}
+        if (segment_len == log_var_len) {
+		return strncmp(segment_begin, log_var_begin, segment_len) == 0;
+	} else if (segment_len < log_var_len) {
+		return strncmp(segment_begin, log_var_begin, segment_len) == 0
+		    && log_var_begin[segment_len] == '.';
+        } else {
+		return false;
+	}
+}
+
+unsigned
+log_var_update_state(log_var_t *log_var) {
+	const char *log_var_begin = log_var->name;
+	const char *log_var_end = log_var->name + strlen(log_var->name);
+
+	/* Pointer to one before the beginning of the current segment. */
+	const char *segment_begin = log_var_names;
+
+	/*
+	 * If log_init done is false, we haven't parsed the malloc conf yet.  To
+	 * avoid log-spew, we default to not displaying anything.
+	 */
+	if (!atomic_load_b(&log_init_done, ATOMIC_ACQUIRE)) {
+		return LOG_INITIALIZED_NOT_ENABLED;
+	}
+
+	while (true) {
+		const char *segment_end = log_var_extract_segment(
+		    segment_begin);
+		assert(segment_end < log_var_names + JEMALLOC_LOG_BUFSIZE);
+		if (log_var_matches_segment(segment_begin, segment_end,
+		    log_var_begin, log_var_end)) {
+			atomic_store_u(&log_var->state, LOG_ENABLED,
+			    ATOMIC_RELAXED);
+			return LOG_ENABLED;
+		}
+		if (*segment_end == '\0') {
+			/* Hit the end of the segment string with no match. */
+			atomic_store_u(&log_var->state,
+			    LOG_INITIALIZED_NOT_ENABLED, ATOMIC_RELAXED);
+			return LOG_INITIALIZED_NOT_ENABLED;
+		}
+		/* Otherwise, skip the delimiter and continue. */
+		segment_begin = segment_end + 1;
+	}
+}