This commit is a large set of code changes and results in removal of
hundreds, perhaps thousands, of CPU instructions, a portion of which
are on hot code paths.
Most (buffer *) used by lighttpd are not NULL, especially since buffers
were inlined into numerous larger structs such as request_st and chunk.
In the small number of instances where that is not the case, a NULL
check is often performed earlier in a function where that buffer is
later used with a buffer_* func. In the handful of cases that remained,
a NULL check was added, e.g. with r->http_host and r->conf.server_tag.
- check for empty strings at config time and set value to NULL if blank
string will be ignored at runtime; at runtime, simple pointer check
for NULL can be used to check for a value that has been set and is not
blank ("")
- use buffer_is_blank() instead of buffer_string_is_empty(),
and use buffer_is_unset() instead of buffer_is_empty(),
where buffer is known not to be NULL so that NULL check can be skipped
- use buffer_clen() instead of buffer_string_length() when buffer is
known not to be NULL (to avoid NULL check at runtime)
- use buffer_truncate() instead of buffer_string_set_length() to
truncate string, and use buffer_extend() to extend
Examples where buffer known not to be NULL:
- cpv->v.b from config_plugin_values_init is not NULL if T_CONFIG_BOOL
(though we might set it to NULL if buffer_is_blank(cpv->v.b))
- address of buffer is arg (&foo)
(compiler optimizer detects this in most, but not all, cases)
- buffer is checked for NULL earlier in func
- buffer is accessed in same scope without a NULL check (e.g. b->ptr)
internal behavior change:
callers must not pass a NULL buffer to some funcs.
- buffer_init_buffer() requires non-null args
- buffer_copy_buffer() requires non-null args
- buffer_append_string_buffer() requires non-null args
- buffer_string_space() requires non-null arg
(optional addition to (data_string *), used by http_header.[ch])
extend (data_string *) instead of creating another data_* TYPE_*
(new data type would probably have (data_string *) as base class)
(might revisit choice in the future)
HTTP_HEADER_UNSPECIFIED has been removed. It was used in select
locations as an optimization to avoid looking up enum header_header_e
before checking the array, but the ordering in the array now relies
on having the id. Having the id allows for a quick check if a common
header is present or not in the htags bitmask, before checking the
array, and allows for integer comparison in the log(n) search of the
array, instead of strncasecmp().
With HTTP_HEADER_UNSPECIFIED removed, add optimization to set bit
in htags for HTTP_HEADER_OTHER when an "other" header is added,
but do not clear the bit, as there might be addtl "other" headers
header field-names are required to be lowercase for HTTP/2
so specialize http_header_hkey_get() as http_header_hkey_get_lc()
for simpler comparison
lowercase field-names in http_headers[], as it does not matter for
buffer_eq_icase_ssn(), which is used with http_headers[] for HTTP/1.x
(thx avij)
clients should send a single Cookie header with multiple cookie values
separated with ';'.
https://tools.ietf.org/html/rfc6265#section-4.2.1
However, HTTP/2 loosens this requirement for Cookie.
https://tools.ietf.org/html/rfc7540#section-8.1.2
Section 8.1.2.5 Compressing the Cookie Header Field
and some HTTP/2 clients (Chrome, Firefox) send multiple
'cookie:' headers in a HEADERS frame.
stricter parse of numerical digits for http status code, port num,
and a few other places. (stricter parse than that of strtol())
content ranges are still parsed more loosely at points of use
NB: r->tmp_buf == srv->tmp_buf (pointer is copied for quicker access)
NB: request read and write chunkqueues currently point to connection
chunkqueues; per-request and per-connection chunkqueues are
not distinct from one another
con->read_queue == r->read_queue
con->write_queue == r->write_queue
NB: in the future, a separate connection config may be needed for
connection-level module hooks. Similarly, might need to have
per-request chunkqueues separate from per-connection chunkqueues.
Should probably also have a request_reset() which is distinct from
connection_reset().
return (data_unset *) from array_get_element_klen() to prep for
putting buffer into data_string for value member, rather than as
(buffer *)
(allow in-place modification of these buffer values)
array_get_element_klen() is now intended for read-only access
array_get_data_unset() is used by config processing for r/w access
array_get_buf_ptr() is used for r/w access to ds->value (string buffer)
mark array_get_index() as hot, rewrite to be pure and return sorted pos
mark routines as pure, as appropriate
mark routines as cold if used only at startup for config processing
mark params const, as appropriate
array_get_buf_ptr() for modifiable value buffer after insert into array
uint32_t used and size members instead of size_t
remove a->unique_ndx member; simply add to end of array for value lists
remove du->is_index_key member; simply check buffer_is_empty(du->key)
array_insert_key_value() used to be a hint that lookup could be skipped,
but the state from array_get_index() is now saved and reused internally,
so the distinction is no longer needed. Use array_set_key_value().
