Daemon: Let daemon actions be numbered from 1

[libucw.git] / ucw / doc / fastbuf.txt

diff --git a/ucw/doc/fastbuf.txt b/ucw/doc/fastbuf.txt
index 754acd3e85bf023ed9e4eb5c0800b9a552b99884..13590a5dd431101a97ae3baec0b3947f6f8915c2 100644 (file)
--- a/ucw/doc/fastbuf.txt
+++ b/ucw/doc/fastbuf.txt
@@ -1,12 +1,46 @@
 Fastbufs
 ========
 
-Fastbufs are stream and file abstractions. They work with normal
-files, network sockets, memory buffers or just any file descriptor. It
-should be easy to implement other types by providing functions to
-refill and read the buffer.
+A *fastbuf* is a stream (or file) abstraction optimized for both speed
+and flexibility.
 
-Apart from abstraction, they are very fast.
+Fastbufs can represent many different kinds of objects: regular files, network
+sockets, file descriptors in general, or various memory buffers. These objects
+are handled by different fastbuf *back-ends.*
+
+Once you have a fastbuf, you can access it by fuctions similar to those of
+`stdio.h`, or you can use a variety of fastbuf *front-ends* providing various
+formatted operations.
+
+Please keep in mind that fastbufs do not allow arbitrary mixing of reads and
+writes on the same stream. If you need to mix them, you have to call @bflush()
+inbetween and remember that the file position reported by @btell() points after
+the flushed buffer, which is not necessarily the same as after the data you've
+really read.
+
+Fastbufs can also participate in the libucw resource management system.
+You can tie a fastbuf to a resource in the current resource pool by @fb_tie().
+When the pool gets cleaned up, the fastbuf is automatically closed. If you call
+@bclose() explicitly, the resource is removed, too.
+
+.Back-ends:
+- <<fbparam,Files (parametrized)>>
+- <<fbfile,Regular files>>
+- <<fbtemp,Temporary files>>
+- <<fblim,File fragments>>
+- <<fbmem,In-memory streams>>
+- <<fbbuf,Buffers>>
+- <<fbgrow,Growing buffers>>
+- <<fbpool,Memory pools>>
+- <<fbatomic,Atomic files>>
+
+.Front-ends:
+- <<ffbasic,Basic functions>>
+
+.Other reading:
+- <<internal,Internal structure>>
+- <<bconfig,Configuring streams>>
+- <<fbexc,Exceptions>>
 
 ucw/fastbuf.h
 -------------
@@ -25,11 +59,26 @@ ucw/ff-unicode.h
 
 Reading and writing of unicode characters.
 
-Invalid codes are replaced by +UNI_REPLACEMENT+ when reading.
+Invalid codes are replaced by `UNI_REPLACEMENT` when reading.
 
 !!ucw/ff-unicode.h
 
 ucw/ff-binary.h
 ---------------
 
-Reading and writing of binary values.
+!!ucw/ff-binary.h
+
+Exceptions [[fbexc]]
+--------------------
+
+All standard back-ends and front-ends raise exceptions on errors. All such
+exceptions live in the `ucw.fb` subtree. The following exceptions are defined:
+
+`ucw.fb.eof`:: Unexpected end of file (e.g., when the @FB_DIE_ON_EOF flag is set)
+`ucw.fb.mmap`:: Memory mapping failed (e.g., the `mmap` syscall has failed)
+`ucw.fb.open`:: Opening failed (file does not exist and similar problems)
+`ucw.fb.read`:: Read error (e.g., the `read` syscall has failed or the stream is write-only)
+`ucw.fb.seek`:: Seek error (e.g., file not seekable, or a seek behind EOF)
+`ucw.fb.tmp`:: Creation of temporary file failed
+`ucw.fb.toolong`:: Object (typically a line) is too long
+`ucw.fb.write`:: Write error (e.g., the `write` syscall has failed or the stream is read-only)