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-rw-r--r--src/shared/strbuf.c20
1 files changed, 20 insertions, 0 deletions
diff --git a/src/shared/strbuf.c b/src/shared/strbuf.c
index 5c858cb68e..9314f097ab 100644
--- a/src/shared/strbuf.c
+++ b/src/shared/strbuf.c
@@ -25,6 +25,23 @@
#include "util.h"
#include "strbuf.h"
+/*
+ * Strbuf stores given strings in a single continous allocated memory
+ * area. Identical strings are de-duplicated. If the tail of a string
+ * already exist in the buffer, the tail is returned.
+ *
+ * A Particia Trie is used to maintain the information about the stored
+ * strings.
+ *
+ * Example of udev rules:
+ * $ ./udevadm test .
+ * ...
+ * read rules file: /usr/lib/udev/rules.d/99-systemd.rules
+ * rules contain 196608 bytes tokens (16384 * 12 bytes), 39742 bytes strings
+ * 23939 strings (207859 bytes), 20404 de-duplicated (171653 bytes), 3536 trie nodes used
+ * ...
+ */
+
struct strbuf *strbuf_new(void) {
struct strbuf *str;
@@ -58,6 +75,7 @@ static void strbuf_node_cleanup(struct strbuf_node *node) {
free(node);
}
+/* clean up trie data, leave only the string buffer */
void strbuf_complete(struct strbuf *str) {
if (!str)
return;
@@ -66,6 +84,7 @@ void strbuf_complete(struct strbuf *str) {
str->root = NULL;
}
+/* clean up everything */
void strbuf_cleanup(struct strbuf *str) {
if (!str)
return;
@@ -82,6 +101,7 @@ static int strbuf_children_cmp(const void *v1, const void *v2) {
return n1->c - n2->c;
}
+/* add string, return the index/offset into the buffer */
ssize_t strbuf_add_string(struct strbuf *str, const char *s, size_t len) {
uint8_t c;
struct strbuf_node *node;