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Performance tweak to evhttp_parse_request_line.

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Method parsing has been tweaked out to use a lookup table instead of multiple
branching. In our testing it has increased performance by a fair bit.
This commit is contained in:
Mark Ellzey 2011-05-06 08:48:54 -04:00
parent 18f24ef4d5
commit aee1a97da4
1 changed files with 114 additions and 21 deletions
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135
http.c
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@ -1470,6 +1470,8 @@ evhttp_parse_request_line(struct evhttp_request *req, char *line)
char *version; char *version;
const char *hostname; const char *hostname;
const char *scheme; const char *scheme;
size_t method_len;
enum evhttp_cmd_type type;
/* Parse the request line */ /* Parse the request line */
method = strsep(&line, " "); method = strsep(&line, " ");
@ -1482,30 +1484,121 @@ evhttp_parse_request_line(struct evhttp_request *req, char *line)
if (line != NULL) if (line != NULL)
return (-1); return (-1);
method_len = (uri - method) - 1;
type = _EVHTTP_REQ_UNKNOWN;
/* First line */ /* First line */
if (strcmp(method, "GET") == 0) { switch (method_len) {
req->type = EVHTTP_REQ_GET; case 3:
} else if (strcmp(method, "POST") == 0) { /* The length of the method string is 3, meaning it can only be one of two methods: GET or PUT */
req->type = EVHTTP_REQ_POST;
} else if (strcmp(method, "HEAD") == 0) { /* Since both GET and PUT share the same character 'T' at the end,
req->type = EVHTTP_REQ_HEAD; * if the string doesn't have 'T', we can immediately determine this
} else if (strcmp(method, "PUT") == 0) { * is an invalid HTTP method */
req->type = EVHTTP_REQ_PUT;
} else if (strcmp(method, "DELETE") == 0) { if (method[2] != 'T') {
req->type = EVHTTP_REQ_DELETE; break;
} else if (strcmp(method, "OPTIONS") == 0) { }
req->type = EVHTTP_REQ_OPTIONS;
} else if (strcmp(method, "TRACE") == 0) { switch (*method) {
req->type = EVHTTP_REQ_TRACE; case 'G':
} else if (strcmp(method, "PATCH") == 0) { /* This first byte is 'G', so make sure the next byte is
req->type = EVHTTP_REQ_PATCH; * 'E', if it isn't then this isn't a valid method */
} else {
req->type = _EVHTTP_REQ_UNKNOWN; if (method[1] == 'E') {
event_debug(("%s: bad method %s on request %p from %s", type = EVHTTP_REQ_GET;
}
break;
case 'P':
/* First byte is P, check second byte for 'U', if not,
* we know it's an invalid method */
if (method[1] == 'U') {
type = EVHTTP_REQ_PUT;
}
break;
default:
break;
}
break;
case 4:
/* The method length is 4 bytes, leaving only the methods "POST" and "HEAD" */
switch (*method) {
case 'P':
if (method[3] == 'T' && method[2] == 'S' && method[1] == 'O') {
type = EVHTTP_REQ_POST;
}
break;
case 'H':
if (method[3] == 'D' && method[2] == 'A' && method[1] == 'E') {
type = EVHTTP_REQ_HEAD;
}
break;
default:
break;
}
case 5:
/* Method length is 5 bytes, which can only encompass PATCH and TRACE */
switch (*method) {
case 'P':
if (method[4] == 'H' && method[3] == 'C' && method[2] == 'T' && method[1] == 'A') {
type = EVHTTP_REQ_PATCH;
}
break;
case 'T':
if (method[4] == 'E' && method[3] == 'C' && method[2] == 'A' && method[1] == 'R') {
type = EVHTTP_REQ_TRACE;
}
break;
default:
break;
}
break;
case 6:
/* Method length is 6, only valid method 6 bytes in length is DELEte */
/* If the first byte isn't 'D' then it's invalid */
if (*method != 'D') {
break;
}
if (method[5] == 'E' && method[4] == 'T' && method[3] == 'E' && method[2] == 'L' && method[1] == 'E') {
type = EVHTTP_REQ_DELETE;
}
break;
case 7:
/* Method length is 7, only valid methods are "OPTIONS" and "CONNECT" */
switch (*method) {
case 'O':
if (method[6] == 'S' && method[5] == 'N' && method[4] == 'O' &&
method[3] == 'I' && method[2] == 'T' && method[1] == 'P') {
type = EVHTTP_REQ_OPTIONS;
}
break;
case 'C':
if (method[6] == 'T' && method[5] == 'C' && method[4] == 'E' &&
method[3] == 'N' && method[2] == 'N' && method[1] == 'O') {
type = EVHTTP_REQ_CONNECT;
}
break;
default:
break;
}
break;
} /* switch */
if (type == _EVHTTP_REQ_UNKNOWN) {
event_debug(("%s: bad method %s on request %p from %s",
__func__, method, req, req->remote_host)); __func__, method, req, req->remote_host));
/* No error yet; we'll give a better error later when /* No error yet; we'll give a better error later when
* we see that req->type is unsupported. */ * we see that req->type is unsupported. */
} }
req->type = type;
if (evhttp_parse_http_version(version, req) < 0) if (evhttp_parse_http_version(version, req) < 0)
return (-1); return (-1);