ACE+TAO Subsetting

We are involved in ongoing activities to subset ACE+TAO to make them more flexible and to reduce their memory footprint for embedded systems. This document describes what we've done thus far, what we're planning to do next, and how to leverage our efforts to minimize the size of your ACE+TAO applications.

Contents

Motivation for Splitting ACE into Multiple Libraries
Configuration Management
Classes in Each ACE Library Subset
ACE Library Size Breakdown
Building ACE Subsets
ACE_OS Adaptation Layer
Minimum TAO
The Shared Library Reduction (soreduce) tool
ACE+TAO Subsetting Work in Progress

Motivation for Splitting ACE into Multiple Libraries

This document describes how we are splitting ACE into multiple libraries, each of which will contain a smaller subset of the overall ACE functionality. The primary motivations for subsetting ACE are:

Principle of parsimony -- i.e., developers should incur time/space overhead for components they use, rather than for all the components in the ACE framework.
Simplify the learning curve -- i.e., developers only need to learn how to program components that they actually use.

The main design goals of our approach are as follows:

Support the original libACE as before. Thus, for users who want to use the existing ACE library as is, there will be no changes, i.e., just link with libACE as usual.
Allow ACE (and TAO) programmers to use smaller subsets of the entire libACE library. These subsets will include the following libraries:

libACE_OS -- This library contains the OS adaptation layer and its supporting classes. All other ACE libraries will depend on libACE_OS and it will depend on no other ACE libraries.

libACE_Utils -- This library contains the various ACE container classes and other miscellaneous classes, such as Singleton, auto_ptr, timers, etc. This library will depend only on libACE_OS.

libACE_Logging -- This library contains the various ACE logging and tracing classes. This library will depend only on libACE_OS.

libACE_Threads -- This library contains the ACE thread/process management and synchronization classes. This library will depend only on libACE_OS.

libACE_Demux -- This library contains the ACE Reactor and Proactor classes. This library will depend on libACE_OS and libACE_Thread.

libACE_Connection -- This library contains the ACE Connection components, i.e., Acceptor, Connector, and Svc_Handler. This library will depend on libACE_OS, libACE_Thread, and libACE_Demux.

libACE_Sockets -- This library contains the ACE C++ wrappers for sockets. This library will depend on libACE_OS.

libACE_IPC -- This library contains all the ACE C++ wrappers for the other types of IPC and FILE I/O other than sockets. This library will depend on libACE_OS and libACE_Sockets.

libACE_Timer -- This library contains the ACE C++ wrappers for timer support. This library will depend on libACE_OS.

libACE_Svcconf -- This library contains the ACE C++ wrappers for the Service Configurator. This library will depend on libACE_OS, libACE_Demux, libACE_Thread, and libACE_Sockets.

libACE_Streams -- This library contains the ACE Streams classes. This library will depend on libACE_OS, libACE_Demux, and libACE_Thread.

libACE_Memory -- This library contains the ACE C++ wrappers for shared memory and memory-mapped files. This library will depend on libACE_OS.

libACE_Token -- This library contains the ACE C++ wrappers for token support. This library is not needed by TAO.

libACE_Other -- This library contains miscellaneous code, primarily including a CORBA interface and naming support. It is not actively supported, and is not needed by TAO. Its functionality is included in TAO.

We are also planning to support the OMG's Minimum CORBA specification as part of a separate effort. Preliminary results of prototypes for Minimum CORBA we've integrate to TAO have been very promising, yielding a 40% reduction in ORB footprint.

Note that the ACE library subsets described above are intended as a guideline, not a complete specification. The actual partitioning of files in the final ACE library subsets may differ somewhat to improve footprint and simplify common use-cases.

Configuration Management

Configuration management for the ACE library subsets described above will be organized as follows:

A single source tree with a single "version" for the source tree.
Releases of libACE and its "subsets" will be atomic, i.e., all or nothing.

Classes in Each ACE Library Subset

Below, we describe the classes in each ACE library subset.

libACE_OS

This library contains the OS adaptation layer and its supporting classes. The classes in this library should not depend on any other ACE library subsets. All of the other libraries will depend on this library. The following classes are included in this library.


  ARGV 
  Argv_Type_Converter 
  Basic_Types 
  Time_Value 
  OS 
  OS_Dirent 
  OS_Memory 
  OS_QoS 
  OS_String 
  OS_TLI 
  OS_Errno 
  Base_Thread_Adapter 
  OS_Thread_Adapter 
  OS_Log_Msg_Attributes 
  Thread_Hook 
  Sched_Params 
  Handle_Set 
  Copy_Disabled

libACE_Utils

This library contains the following ACE container classes and other miscellaneous classes.


  ACE 
  Active_Map_Manager 
  Arg_Shifter 
  Capabilities 
  Containers 
  Configuration 
  Configuration_Import_Export 
  Dirent 
  Dirent_Selector 
  Dynamic 
  Flag_Manip 
  Framework_Component 
  Functor 
  Get_Opt 
  Hash_Map_Manager 
  Connection_Recycling_Strategy 
  Hashable 
  Notification_Strategy 
  Recyclable 
  Refcountable 
  Handle_Ops 
  Init_ACE 
  Lib_Find 
  Message_Block 
  Method_Request 
  Object_Manager 
  Registry 
  String_Base_Const 
  SString 
  Stats 
  Sample_History

libACE_Logging

This library contains the various ACE logging and tracing classes.


  Dump 
  Log_Msg 
  Log_Msg_Callback 
  Log_Msg_Backend 
  Log_Msg_IPC 
  Log_Msg_NT_Event_Log 
  Log_Msg_UNIX_Syslog 
  Log_Record 
  Logging_Strategy 
  Trace

libACE_Threads

This library contains the ACE thread/process management and synchronization classes.


  Activation_Queue 
  Process 
  Process_Manager 
  Synch 
  Synch_Options 
  Process_Semaphore 
  Process_Mutex 
  RW_Process_Mutex 
  File_Lock 
  Thread 
  Thread_Manager 
  Thread_Adapter 
  Thread_Exit 
  Thread_Control 
  Token

libACE_Demux

This library contains the ACE Reactor and its associated classes, including the ACE Connection components.


  Event_Handler 
  FlReactor 
  Msg_WFMO_Reactor 
  POSIX_Proactor 
  POSIX_CB_Proactor 
  WIN32_Proactor 
  Priority_Reactor 
  Proactor 
  Reactor 
  Select_Reactor 
  Select_Reactor_Base 
  SUN_Proactor 
  Dev_Poll_Reactor 
  TP_Reactor 
  TkReactor 
  WFMO_Reactor 
  XtReactor 
  QtReactor

libACE_Connection

This library contains the ACE Connection components, i.e., Acceptor, Connector, and Svc_Handler.


  Asynch_IO 
  Asynch_IO_Impl 
  Asynch_Pseudo_Task 
  POSIX_Asynch_IO 
  WIN32_Asynch_IO

libACE_Sockets

This library contains the ACE C++ wrappers for sockets.


  Addr 
  INET_Addr 
  IPC_SAP 
  LSOCK 
  LSOCK_Acceptor 
  LSOCK_CODgram 
  LSOCK_Connector 
  LSOCK_Dgram 
  LSOCK_Stream 
  SOCK 
  SOCK_Acceptor 
  SOCK_CODgram 
  Sock_Connect 
  SOCK_Connector 
  SOCK_Dgram 
  SOCK_Dgram_Bcast 
  SOCK_Dgram_Mcast 
  SOCK_IO 
  SOCK_Stream

libACE_IPC

This library contains all the ACE C++ wrappers for the other types of IPC and FILE I/O other than sockets. This library will depend on the libACE_Socket library.


  ATM_Addr 
  ATM_Acceptor 
  ATM_Connector 
  ATM_Params 
  ATM_QoS 
  ATM_Stream 
  XTI_ATM_Mcast 
  DEV 
  DEV_Addr 
  DEV_Connector 
  DEV_IO 
  FIFO 
  FIFO_Recv 
  FIFO_Recv_Msg 
  FIFO_Send 
  FIFO_Send_Msg 
  FILE_Addr 
  FILE 
  FILE_Connector 
  FILE_IO 
  IO_SAP 
  IOStream 
  Pipe 
  Signal 
  SPIPE_Addr 
  SPIPE 
  SPIPE_Acceptor 
  SPIPE_Connector 
  SPIPE_Stream 
  SV_Message 
  SV_Message_Queue 
  SV_Semaphore_Complex 
  SV_Semaphore_Simple 
  SV_Shared_Memory 
  TLI 
  TLI_Acceptor 
  TLI_Connector 
  TLI_Stream 
  TTY_IO 
  UNIX_Addr 
  UPIPE_Acceptor 
  UPIPE_Connector 
  UPIPE_Stream 
  MEM_Acceptor 
  MEM_Addr 
  MEM_Connector 
  MEM_IO 
  MEM_SAP 
  MEM_Stream

libACE_Svcconf

This library contains the ACE C++ wrappers for the Service Configurator component.


  DLL 
  DLL_Manager 
  Dynamic_Service_Base 
  Parse_Node 
  Service_Config 
  Service_Manager 
  Service_Object 
  Service_Repository 
  Service_Types 
  Service_Templates 
  Shared_Object 
  XML_Svc_Conf 
  Svc_Conf_l 
  Svc_Conf_y 
  Svc_Conf_Lexer_Guard

libACE_Streams

This library contains the ACE Streams classes.


  CDR_Base 
  CDR_Stream 
  Codeset_IBM1047 
  Message_Queue 
  Reactor_Notification_Strategy 
  Task

libACE_Memory

This library contains the ACE C++ wrappers for shared memory and memory-mapped files.


  Based_Pointer_Repository 
  Malloc 
  PI_Malloc 
  Malloc_Allocator 
  Malloc_Instantiations 
  Mem_Map 
  Memory_Pool 
  Obchunk 
  Obstack 
  Read_Buffer 
  Shared_Memory 
  Shared_Memory_MM 
  Shared_Memory_SV

libACE_Timer

This componenty contains the ACE C++ wrappers for the ACE timer classes.


  Basic_Stats 
  High_Res_Timer 
  Profile_Timer 
  System_Time 
  Time_Request_Reply 
  Timeprobe 
  Timer_Hash 
  Timer_Heap 
  Timer_List 
  Timer_Queue 
  Timer_Wheel

libACE_Token

This componenty contains the ACE C++ wrappers for Token classes.


  Local_Tokens 
  Remote_Tokens 
  Token_Collection 
  Token_Invariants 
  Token_Manager 
  Token_Request_Reply

libACE_Codec

This component contains the ACE codec support:


  Codecs

libACE_Other

This component contains miscellaneous ACE C++ wrappers:


  Local_Name_Space 
  Name_Proxy 
  Name_Request_Reply 
  Name_Space 
  Naming_Context 
  Registry_Name_Space 
  Remote_Name_Space

ACE Library Size Breakdown

Here is an example size breakdown, by ACE library component. It is for the ACE 5.0 libACE.a, statically built with these make flags:


    debug=0 optimize=1 static_libs_only=1 DEFFLAGS=-DACE_USE_RCSID=0

These options translate into:

(a) No debugging,
(b) Optimization is set to -O2,
(c) Static ACE and TAO libraries, and
(d) Use of RCS Ids is turned off.

To build an ACE static library, if shared libraries are the default, use make static_libs_only=1. If you're using recent versions of GNU GCC, you can use the -frepo option, which typically reduces the footprint by another 25 percent.

Platform	Component	Total	For TAO subset	OS	Utils	Logging	Threads	Demux	Con- nection	Sockets	IPC	Svcconf	Streams	Memory	Token	Other
Linux (RedHat 6.0/Intel) egcs 2.91.66	Size, bytes	648727	515501	10937	118305	13544	59593	74629	49933	16084	34820	92192	18462	27002	71574	61652
Linux (RedHat 6.0/Intel) egcs 2.91.66	Percentage of total size	100	79.46	1.69	18.24	2.09	9.19	11.50	7.70	2.48	5.37	14.21	2.85	4.16	11.03	9.50
LynxOS 3.0.0 g++ 2.7-97r1	Size, bytes	582672	475216	25620	97220	11000	44192	71388	58100	13120	31572	77972	21468	23564	60832	46624
LynxOS 3.0.0 g++ 2.7-97r1	Percentage of total size	100	81.56	4.40	16.69	1.89	7.58	12.25	9.97	2.25	5.42	13.38	3.68	4.04	10.44	8.00
SunOS5.7 egcs 2.91.60	Size, bytes	709543	570693	11877	115306	13721	63027	87962	68551	16917	42954	99839	21357	29182	75970	62880
SunOS5.7 egcs 2.91.60	Percentage of total size	100	80.43	1.67	16.25	1.93	8.88	12.40	9.66	2.38	6.05	14.07	3.01	4.11	10.71	8.86
SunOS 5.7 GreenHills 1.8.9	Size, bytes	803651	653787	15800	146633	18544	69172	103584	60580	23084	52986	108200	21528	33676	79324	70540
SunOS 5.7 GreenHills 1.8.9	Percentage of total size	100	81.35	1.97	18.25	2.31	8.61	12.89	7.54	2.87	6.59	13.46	2.68	4.19	9.87	8.78
SunOS 5.7 Sun C++ 4.2	Size, bytes	626824	494501	15502	64929	15605	63364	106841	55013	19945	73584	46434	19685	25952	69843	62480
SunOS 5.7 Sun C++ 4.2	Percentage of total size	100	78.89	2.47	10.36	2.49	10.11	17.04	8.78	3.18	11.74	7.41	3.14	4.14	11.14	9.97
VxWorks 5.3.1 GreenHills 1.8.8	Size, bytes	689564	542628	22252	145036	19664	63640	54296	980	22120	47468	117932	23220	27220	78900	68036
VxWorks 5.3.1 GreenHills 1.8.8	Percentage of total size	100	78.69	3.23	21.03	2.85	9.23	7.87	0.14	3.21	6.88	17.10	3.37	3.95	11.44	9.87
VxWorks 5.3.1 g++ cygnus- 2.7.2-960126 (with implicit templates)	Size, bytes	1051540	888244	36484	140832	14344	66740	266192	14480	15084	106308	142500	55932	29348	88564	74732
	Percentage of total size	100	84.47	3.47	13.39	1.36	6.35	25.31	1.38	1.43	10.11	13.55	5.32	2.79	8.42	7.11

It has also been observed recently that using -xO3 with -xspace on SUN CC 5.3 compiler gives a big footprint reduction of the order of 40%

Building ACE Subsets

By default, the ACE library contains all of the components that ACE currently supports. To reduce build time and library size, you can exclude unused components. To do that, define an ACE_COMPONENTS variable using this approach:

In your $(ACE_ROOT)/include/makeinclude/platform_macros.GNU file, e.g., add:
```
ACE_COMPONENTS = OS
```
or
On the make command line, e.g.,
```
make ACE_COMPONENTS=OS
```
or
Set (and export) the ACE_COMPONENTS environment variable to contain the components that you want to build.

Please see ../ace/Makefile for the default contents of ACE_COMPONENTS.

A special value of ACE_COMPONENTS can be used to build an ACE library that supports TAO. The special value is FOR_TAO. So, for example, you can add this to your $(ACE_ROOT)/include/makeinclude/platform_macros.GNU to restrict ACE support to just that which is needed for TAO:


ACE_COMPONENTS = FOR_TAO

Please note the current limitations:

We currently don't check for interdependencies between components. For example, if you build any component beside OS, you must explicitly include OS in your ACE_COMPONENTS.
We currently don't check this macro in other ACE or TAO Makefiles, or in their tests. We'll add those checks as time allows.
This is only supported by the gmake Makefiles. For example, the MSVC projects on Win32 do not support the specification of components.

ACE_OS Adaptation Layer

The lowest-level component, OS, is also called the ACE_OS adaption layer. It provides the ACE interface to the underlying operating system, but little else. It can be used standalone.

To create the ACE_OS adaptation layer, build your libACE with ACE_COMPONENTS set to OS. In addition, add #include "ace/config-minimal.h" to your ACE_wrappers/ace/config.h file.

When using the ACE_OS adaptation layer, you'll be limited to the the ACE_OS member functions, ACE's Basic_Types and Sched_Params, and macros defined in ace/OS.h. See ACE's Basic_Types_Test.cpp for an example of usage.

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