🔗 Feature: Source layout improvements

• Goal: Ease code navigation. Reduce recompilation time. Fix distclean. Fix dependency tree.
• Status: In progress
• ETA: Ongoing
• Version: 3.3
• Developer: AlexRousskov and AmosJeffries
• More: email07121 email07506

Historically, many Squid source files have been dumped into squid/src directory. That directory has accumulated more than 400 source files. This project will group closely related files and place groups in individual directories. The squid/src directory will contain pretty much nothing but Makefiles and subdirectories.

🔗 Squid Source Code Layout

This section is used to edit and finalize the grouping of source files. The Group column contains src/ subdirectory names. The Files section lists current file names and assumes file extensions .h, .cc, and .cci are added to the corresponding file names and masks.

Key:

• (empty) - not even checked yet to see if this needs doing.
• :frown: in a sad state of affairs.
• Done.
• Improved, but needs more work. Nobody is working on this now. See the To-do column for details.

Unit Tests	Stub	Namespace	forward.h	Polish	Group	Definition	Files and To-do
	-	-	-		~/compat/	Portability primitives. This is a full layer below everything, should be seamless with the OS API.	** migrate remaining pieces from squid.h and squid-old.h into compat
					acl/	Access Controls	ACLexternal_acl., Add Acl namespace and rename classes?
					adaptation/	code common to eCAP and ICAP
					adaptation/ecap/	eCAP support
					adaptation/icap/	ICAP support
					anyp/	Protocol-independent protocol primitives	urlurn ProtoPort*
					auth/	Authentication schemes
					auth/basic/	Basic Authentication
					auth/digest/	Digest Authentication
					auth/negotiate/	Negotiate Authentication
					auth/ntlm/	NTLM Authentication
					base/	Commonly used code without a better place to go.	Async? wordlist. dlink.hash.
					clientdb/	Database of information about clients	PR 954 client_db.*
					clients/	Protocol clients and gateway components for connecting to upstream servers	ftp., http., gopher.*
					comm/	I/O subsystem
					cfg/	squid.conf parsing and management	PR 928, cache_cf.cf. cf_* Parser.* ConfigParser.* ConfigOption.*
					debug/	Debug core utilities
					DiskIO	I/O primitives for filesystem access
					dns/	DNS components (Internal, dnsserver, caches)	dns, ipcache. fqdncache.*
					esi/	ESI support	ESI*, Add Esi namespace, rename classes
					eui/	EUI-48 / MAC / ARP operations
					format/	Custom formatting
					fs/	file system-specific cache store support?	rename classes, add Makefiles for subdirs.
	-	-		-	fs/aufs	AUFS cache_dir	Fs::Ufs namespace, renamed files. TODO: rename classes
	-	-		-	fs/diskd	DiskD cache_dir	FrancescoChemolli. Fs::Ufs namespace, renamed files. TODO: rename classes
					fs/ufs	Ufs cache_dir	TODO: rename classes
					fs/rock	Rock cache_dir	TODO: rename classes
					ftp/	FTP primitives shared by client, server, and ICAP sides
					helper/	Features/AddonHelpers protocol primitives	migrate helper.*
					http/	HTTP primitives shared by client, server, and ICAP sides	Http*
					http/one/	HTTP/1 primitives shared by client, server, and ICAP sides
					http/two/	HTTP/2 primitives shared by client, server, and ICAP sides
					icmp/	ICMP support and Network measurement	Icmpnet_db., C++ convert net_db*, Add Icmp namespace and rename classes
					ident/	IDENT support	ident.* Make remote connection handling into an AsyncJob
					ip/	IP Protocol	IpQos
					ipc/	inter-process communication	ipc.ipc_win32., Move files, add Ipc namespace to them, and adjust global names
					log/	Logging components	namespace for Custom log formats and tokenizer. classify
					mem/	Basic Memory management	class renaming, documentation, unit tests
					mgr/	Cache Manager	Move in CacheManager.h, cache_manager.cc, and test cases
					parser/	generic parsing primitives
					proxyp/	PROXY protocol primitives
					redirect/	URL alteration (redirectors, URL-rewrite, URL maps)	redirect.RedirectInternal.
					repl/heap/	HEAP Replacement Policy algorithms
					repl/lru/	Cache Replacement Policy algorithms
					sbuf/	SBuf (string buffer) components and related algorithms
					security/	Transport Layer Security components
					security/sspi/	Windows Security Support Provider Interface
					servers/	Listening Server components for receiving connections	client_side*
					snmp/	SNMP components	snmp_*, move core and agent code. restructure for extensibility.
					ssl/	OpenSSL components	library is named libsslsquid.la and matchgin stub_lib*.cc
					shaping/	Traffic shaping and delay pools	PR 928, [Dd]elay. [Pp]ool.*
					store/	generic (fs-agnostic) disk and memory cache support?	Storestore
					time/	time and date handling tools	PR 1001

🔗 Bundled Add-On Source code

This section is used to edit and finalize the grouping of source files important for users but not integral to build Squid. These sources are generally contributed by third parties and vetted by the Squid Developers for bundling.

Directory Path	Content Type
src/adaptation/ecap/modules/*	(PROPOSED) eCAP extension modules which may be linked by configuration.
src/auth/basic/*/	auth_param basic helpers
src/auth/digest/*/	auth_param digest helpers
src/auth/negotiate/*/	auth_param negotiate helpers
src/auth/ntlm/*/	auth_param ntlm helpers
src/acl/external/*	external_acl_type helpers
src/fs/diskd/*	diskd_program Disk I/O helpers
src/fs/unlink/*	(PROPOSED) unlinkd_program helpers
src/http/url_rewriters/*	HTTP message URL re-writers (url_rewrite_program)
src/icmp/*	pinger_program helpers
src/log/*/	logfile_daemon helpers
src/security/cert_validators/*	sslcrtvalidator_program helpers
src/security/cert_generators/*	sslcrtd_program helpers
src/security/cert_password/*	(PROPOSED) sslpassword_program helpers
src/store/id_rewriters/*	Store-ID re-writers (store_id_program)
tools/	Administration tools

🔗 Problems

If you know the solution or can improve the proposed one, please write to squid-dev mailing list.

Problem	Proposed solution
Where to put OS-compatibility wrappers that are currently located in squid/lib and squid/include?	squid/compat/ but due to autoconf limitations the code must still be in .c files.
Where to put 3rd party libraries that are currently located in squid/lib and squid/include?	squid/import/libFoo/
Can we remove Foo prefix from FOO/FooSomething.h file names? The prefix carries no additional information and is probably not required for modern compilers, especially in C++ world.	Yes, Carefully File name should match the primary class declared or defined in that file. Directory name should match the (lowercased) namespace used by classes in that directory. We should move from PROTOFoo to PROTO::Foo classes. Ensure that there is no squid/src/Foo.h or squid/include/Foo.h file before using a foo/Foo.h. Some systemic problems have been found cleaning filenames like this with compiler include methods.
Should client- and server- side files be separated?	yes
Should directory names use just_small, CamelCase, or CAPS letters?	lower_case
Should class and file names use just_small, CamelCase, or CAPS letters?	CamelCaseHttpAcronymsIncluded
Should we use squid/src/squid/ root for most sources to include header files as <squid/group/file.h>? This may be required for installed headers and 3rd party code using those headers. It is not clear whether Squid will have installed headers in the foreseeable future. The Feature/eCAP work will determine that.	no
Should we form a generic mini-cache object type to combine the shared portions of fqdncache, ipcache, idns queue, netdb, ident-cache, maybe others not yet found?	Probably, that will be a separate feature event though.
What to do with all the mixed testand stub_ files during this restructure?	Stub files placed next to the .cc file they can replace with an extension of .stub.cc and no file prefix.
test files go in test-suite directory.
What to do with third-party integration scripts and files?	Place in application-specific subdirectories off tools/

🔗 Dependency Issues:

• Cache manager storeAppendPrintf - just about every component uses this old function to dump it’s stats to the cache manager output. It depends on StoreEntry which pulls in the entire store component tree. We need to make it use something something smaller
  • An earlier attempt was made to use StoreEntryStream, but that still pulls in StoreEntry
  • MemBuf is looking like a good all-purpose buffer we can have the components dump their text into. Which is then dumped into a StoreEntry by the cache manager. TODO: this probably should be switched to SBuf or SBufList now.
  • Current approach is to use Packable API:
    • the Packable type defines basic append() and appendf() semantics implemented by relevant classes (MemBuf, StoreEntry, TODO: SBuf).
    • the PackableStream type implements the C++ stream operators for any object implementing the Packable API
• debugs() macro handling still has a small circular dependency with libsquid, libbase files and file IO.

🔗 Testing Architecture

Per developers meeting 2023-10-25:

• restructure src/Makefile.am to link all squid objects and libraries into libsquid.la.
• redesign tests to link libsquid.la
• provide distinct main.cc files for each binary, linked against libsquid.la

🔗 Other

Explicit initialization vs self-initialization

The more I think on this the more I am of the opinion that using
self-registering static/global objects as method of initialization &
registration is generally a mistake. Better if each such class have a
method for initialization, with initialization order explicitly coded in
the main program. Also makes transition to runtime loaded modules easier
and less intrusive as each module can assume the modules it registers
into has been properly initialized already which means it can do a full
initialization.

Regards
Henrik

Current approach is to replace globals with a static function (typically called GetFoo() or Foo::GetInstance() for the foo global) returning a static local variable. The variable should either self-initialize or be carefully initialized by the getter function.

Categories: Feature,WantedFeature

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