jshn: use an avl tree for env variables to speed up processing of bigger json files

Signed-off-by: Felix Fietkau <nbd@openwrt.org>

diff --git a/jshn.c b/jshn.c
index 69cb06f91f75058fecfc9da92c05646398baad0d..e2d90220335c6bbc505dd4de4bd26477abb0e752 100644 (file)
--- a/jshn.c
+++ b/jshn.c
@@ -27,11 +27,13 @@
 #include <getopt.h>
 #include "list.h"
 
+#include "avl.h"
 #include "blob.h"
 #include "blobmsg_json.h"
 
 #define MAX_VARLEN     256
 
+static struct avl_tree env_vars;
 static struct blob_buf b = { 0 };
 
 static const char *var_prefix = "";
@@ -39,6 +41,11 @@ static int var_prefix_len = 0;
 
 static int add_json_element(const char *key, json_object *obj);
 
+struct env_var {
+       struct avl_node avl;
+       char *val;
+};
+
 static int add_json_object(json_object *obj)
 {
        int ret = 0;
@@ -175,13 +182,19 @@ static int jshn_parse(const char *str)
        return 0;
 }
 
+static char *getenv_avl(const char *key)
+{
+       struct env_var *var = avl_find_element(&env_vars, key, var, avl);
+       return var ? var->val : NULL;
+}
+
 static char *get_keys(const char *prefix)
 {
        char *keys;
 
        keys = alloca(var_prefix_len + strlen(prefix) + sizeof("K_") + 1);
        sprintf(keys, "%sK_%s", var_prefix, prefix);
-       return getenv(keys);
+       return getenv_avl(keys);
 }
 
 static void get_var(const char *prefix, const char **name, char **var, char **type)
@@ -191,13 +204,13 @@ static void get_var(const char *prefix, const char **name, char **var, char **ty
        tmpname = alloca(var_prefix_len + strlen(prefix) + 1 + strlen(*name) + 1 + sizeof("T_"));
 
        sprintf(tmpname, "%s%s_%s", var_prefix, prefix, *name);
-       *var = getenv(tmpname);
+       *var = getenv_avl(tmpname);
 
        sprintf(tmpname, "%sT_%s_%s", var_prefix, prefix, *name);
-       *type = getenv(tmpname);
+       *type = getenv_avl(tmpname);
 
        sprintf(tmpname, "%sN_%s_%s", var_prefix, prefix, *name);
-       varname = getenv(tmpname);
+       varname = getenv_avl(tmpname);
        if (varname)
                *name = varname;
 }
@@ -291,12 +304,52 @@ static int usage(const char *progname)
        return 2;
 }
 
+static int avl_strcmp_var(const void *k1, const void *k2, void *ptr)
+{
+       const char *s1 = k1;
+       const char *s2 = k2;
+       char c1, c2;
+
+       while (*s1 && *s1 == *s2) {
+               s1++;
+               s2++;
+       }
+
+       c1 = *s1;
+       c2 = *s2;
+       if (c1 == '=')
+               c1 = 0;
+       if (c2 == '=')
+               c2 = 0;
+
+       return c1 - c2;
+}
+
 int main(int argc, char **argv)
 {
+       extern char **environ;
        bool no_newline = false;
        bool indent = false;
+       struct env_var *vars;
+       int i;
        int ch;
 
+       avl_init(&env_vars, avl_strcmp_var, false, NULL);
+       for (i = 0; environ[i]; i++);
+
+       vars = calloc(i, sizeof(*vars));
+       for (i = 0; environ[i]; i++) {
+               char *c;
+
+               vars[i].avl.key = environ[i];
+               c = strchr(environ[i], '=');
+               if (!c)
+                       continue;
+
+               vars[i].val = c + 1;
+               avl_insert(&env_vars, &vars[i].avl);
+       }
+
        while ((ch = getopt(argc, argv, "p:nir:w")) != -1) {
                switch(ch) {
                case 'p':