mechanism to define per-encoder params
parsed into structured data at startup
compression level is the initial target
deflate.params is a better solution to the deflate.compression-level,
which is a single range 1-9 that is overload and applied to all encoders
without any scaling, even though encoders might have different scales.
x-ref:
"ModDeflate questions (possibly some feature requests too)"
https://redmine.lighttpd.net/boards/2/topics/9786
map deflate.compression-level to ZSTD_c_strategy as the current
enum for ZSTD_strategy is in the range 1 .. 9, which matches the
gzip compression level 1 .. 9 range
x-ref:
"ModDeflate questions (possibly some feature requests too)"
https://redmine.lighttpd.net/boards/2/topics/9786
use deflate.allowed-encodings ordering as server preference list
when choosing an encoding from list in client request Accept header
x-ref:
"ModDeflate questions (possibly some feature requests too)"
https://redmine.lighttpd.net/boards/2/topics/9786
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
use http_chunk_append_file_ref() and http_chunk_append_file_ref_range()
reduce resource usage (number of fds open) by reference counting open
fds to files served, and sharing the fd among FILE_CHUNKs in responses
defer optimization to read small files into memory until after
response_start hooks have a chance to run, e.g. until after
mod_deflate chooses whether or not to serve file from compressed
cache, if deflate.cache-dir is configured
translate config server.modules "mod_compress" to "mod_deflate"
accept compress.* directives, but issue DEPRECATED warning trace
mod_deflate differences from mod_compress:
- mod_compress compress.filetype was exact match; deflate.mimetypes is
prefix match (behavior change might compress longer mimetype matches,
which are likely of similar type and compressability)
- mod_compress always sent entire (compressed) file for Range request
mod_deflate will stream compress range result (not stored in cache)
- mod_compress would short-circuit request with 403 Forbidden error
if request file did not exist (stat() failed) (This behavior was
unfriendly to other handlers)
- mod_compress compress.cache-dir layout differs from deflate.cache-dir
layout; file cache should be cleared (or renamed) when migrating from
mod_compress to mod_deflate
- mod_deflate does not issue Vary: Accept-Encoding if request does not
contain Accept-Encoding. The identity response can be cache by
proxies and served to clients. Historically, some proxies disabled
caching if any Vary: response was seen. If the Vary header is
desirable, mod_deflate code which checks for Accept-Encoding and
compression type can be moved down a few lines to be below the
setting of the Vary response header.
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().
use global rather than passing around (server *) just for that
li_itostrn() and li_utostrn() return string length
(rather than requiring subsequent strlen() to find length)
convert all log_error_write() to log_error() and pass (log_error_st *)
use con->errh in preference to srv->errh (even though currently same)
avoid passing (server *) when previously used only for logging (errh)
Glenn Strauss