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git.ipfire.org Git - thirdparty/squid.git/blob - src/base/Packable.h
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2 * Copyright (C) 1996-2015 The Squid Software Foundation and contributors
4 * Squid software is distributed under GPLv2+ license and includes
5 * contributions from numerous individuals and organizations.
6 * Please see the COPYING and CONTRIBUTORS files for details.
9 #ifndef SQUID_SRC_BASE_PACKABLE_H
10 #define SQUID_SRC_BASE_PACKABLE_H
13 * A uniform interface to store-like modules
18 * We have two major interfaces Comm and Store, which take a variety of
19 * different data buffering objects and have different output actions
20 * to be performed on data.
22 * Store has a nice storeAppend[Printf] capability which makes "storing"
23 * things easy and painless.
25 * Comm lacks commAppend[Printf] because Comm does not handle its own
26 * buffers (no mem_obj equivalent for Comm).
28 * Thus, if one wants to be able to Store _and_ Comm::Write an object, 'e
29 * has to implement almost identical functions for using all the data
30 * storage objects and their associated actions. Doing this for all the
31 * available data storage types is a tedious nightmare of almost-duplicated
37 * Objects inheriting from Packable provide a uniform interface for code to
38 * assemble data before passing to Store and Comm modules.
40 * Packable objects have their own append and printf routines that "know"
41 * where to send incoming data. In case of Store interface, sending data to
42 * storeAppend. Packable buffer objects retain the data such that it can be
43 * flushed later to Comm::Write.
45 * Thus, one can write just one function that will take a Packable object
46 * and either "pack" things for Comm::Write or "append" things to Store,
47 * depending on actual Packable object supplied.
52 virtual ~Packable() {}
54 /// Appends a c-string to existing packed data.
55 virtual void append(const char *buf
, int size
) = 0;
57 /// Append operation with printf-style arguments.
58 void appendf(const char *fmt
,...) PRINTF_FORMAT_ARG2
66 /** Append operation, with vsprintf(3)-style arguments.
68 * \note arguments may be evaluated more than once, be careful
71 virtual void vappendf(const char *fmt
, va_list ap
) = 0;
73 /** start buffering appends (if relevant)
75 * Indicates that a number of small appends are about to
76 * follow so would be detrimental to trigger expensive
79 virtual void buffer() {}
81 /** perform a buffer flush (if relevant)
83 * Used by code such as PackableStream, that assumes the
84 * Packable leads to some form of output buffer.
86 virtual void flush() {}
89 #endif /* SQUID_SRC_BASE_PACKABLE_H */