ACE+TAO Subsetting

We are currently subsetting ACE+TAO to make them more flexible and to reduce their 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

  1. Motivation for Splitting ACE into Multiple Libraries
  2. Configuration Management
  3. Classes in Each ACE Library Subset
  4. ACE Library Size Breakdown
  5. Building ACE Subsets
  6. ACE_OS Adaptation Layer
  7. POSIX ACE (PACE)
  8. Minimum TAO
  9. 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: The main design goals of our approach are as follows:

  1. 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.

  2. Allow ACE (and TAO) programmers to use smaller subsets of the entire libACE library. These subsets will include the following libraries:

    o 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.

    o 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.

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

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

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

    o 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.

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

    o 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.

    o 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.

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

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

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

    o 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:
  1. A single source tree with a single "version" for the source tree.

  2. 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.

config.h
Basic_Types
OS
Sched_Params
Handle_Set

libACE_Utils

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

ACE
Active_Map_Manager
Arg_Shifter
ARGV
Containers
Dirent
Dynamic
Filecache
Functor
Get_Opt
Hash_Map_Manager
High_Res_Timer
Method_Request
Object_Manager
Profile_Timer
Registry
SString
Stats
System_Time
Time_Request_Reply
Timeprobe
Timer_Hash
Timer_Heap
Timer_List
Timer_Queue
Timer_Wheel

libACE_Logging

This library contains the various ACE logging and tracing classes.

Dump
Log_Msg
Log_Record
Trace

libACE_Threads

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

Activation_Queue
Process
Process_Manager
Synch
Synch_Options
Thread
Thread_Manager
Token

libACE_Demux

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

Event_Handler
POSIX_Proactor
Priority_Reactor
Proactor
Reactor
Select_Reactor
Select_Reactor_Base
WFMO_Reactor

libACE_Connection

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

Asynch_IO
Asynch_IO_Impl
POSIX_Asynch_IO
Strategies

libACE_Sockets

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

IPC_SAP
LSOCK
LSOCK_Acceptor
LSOCK_CODgram
LSOCK_Connector
LSOCK_Dgram
LSOCK_Stream
SOCK
SOCK_Acceptor
SOCK_CODgram
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.

Addr
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
INET_Addr
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

libACE_Svcconf

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

DLL
Parse_Node
Service_Config
Service_Manager
Service_Object
Service_Repository
Service_Types
Shared_Object
Svc_Conf_l
Svc_Conf_y

libACE_Streams

This library contains the ACE Streams classes.

CDR_Stream
Message_Block
Message_Queue
Task

libACE_Memory

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

Malloc
Mem_Map
Memory_Pool
Obstack
Read_Buffer
Shared_Memory
Shared_Memory_MM
Shared_Memory_SV

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_Other

This component contains miscellaneous ACE C++ wrappers.

CORBA_Handler
CORBA_Ref
Local_Name_Space
Msg_WFMO_Reactor
Name_Proxy
Name_Request_Reply
Name_Space
Naming_Context
Registry_Name_Space
Remote_Name_Space
TP_Reactor
XtReactor


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
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
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
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
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
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
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


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:

  1. In your $(ACE_ROOT)/include/makeinclude/platform_macros.GNU file, e.g., add:
    ACE_COMPONENTS = OS
    or

  2. On the make command line, e.g.,
    make ACE_COMPONENTS=OS
    or

  3. 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:

  1. 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.

  2. 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.

  3. 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.


The POSIX ACE (PACE) project is an OS abstraction layer designed for lightweight and/or verified systems. When complete, it will offer these benefits:

  1. A strict POSIX.1-like, low-level interface. Its interface is ``POSIX compatible'' by that we mean as close to POSIX.1 as it can be, given that PACE is not an operating system. To avoid name conflicts with OS APIs, all low-level PACE function names have the pace_ prefix.

  2. The low-level interface is a C file, so that it can be used in both C and C++ programs.

  3. The low-level interface is partitioned into multiple files, one per POSIX.1 section, which will help linkers reduce the footprint for statically linked applications.


Back to the ACE home page.
Back to ACE Documentation Home.