42. Library version mechanism

42.1. Introduction

.intro: This describes the design of a mechanism to be used to determine the version (that is, product, version, and release) of an MPS library.

42.2. Readership

.readership: Any MPS developer.

42.3. Source

.source: Various requirements demand such a mechanism. See request.epcore.160021: There is no way to tell which version and release of the MM one is using.

42.4. Overview

.overview: This is the design for determining which version of the library one has linked against. There are two aspects to the design, allowing humans to determine the version of an MPS library, and allowing programs to determine the version of an MPS library. Only the former is currently designed (a method for humans to determine which version of an MPS library is being used).

.overview.impl: The overall design is to have a distinctive string compiled into the library binary. Various programs and tools will be able to extract the string and display it. The string will identify the version of the MPS begin used.

42.5. Architecture

.arch.structure: The design consists of two components:

  1. .arch.string: A string embedded into any delivered library binaries (which will encode the necessary information).

  2. .arch.proc: Procedures by which the string is modified appropriately whenever releases are made.

  3. .arch.tool: A tool and its documentation (it is expected that standard tools can be used). The tool will be used to extract the version string from a delivered library or an executable linked with the library.

The string will contain information to identify the following items:

  1. .arch.string.platform: the platform being used.

  2. .arch.string.product: the name of the product.

  3. .arch.string.variety: the variety of the product.

  4. .arch.string.version: the version and release of the product.

42.6. Implementation

.impl.file: The version string itself is a declared C object MPSVersionString in the file version.c (impl.c.version). It consists of a concatenation of various strings which are defined in other modules.

.impl.variety: The string containing the name of the variety is the expansion of the macro MPS_VARIETY_STRING defined by config.h (impl.h.config).

.impl.product: The string containing the name of the product is the expansion of the macro MPS_PROD_STRING defined by config.h (impl.h.config). Note that there is now only one product, so this is always "mps" (see design.mps.config.req.prod).

.impl.platform: The string containing the name of the platform is the expansion of the macro MPS_PF_STRING defined by mpstd.h (impl.h.mpstd).

.impl.date: The string contains the date and time of compilation by using the __DATE__ and __TIME__ macros defined by ISO C §6.8.8.

.impl.version: The string contains the version and release of the product. This is by the expansion of the macro MPS_RELEASE which is defined in this module (version.c).

.impl.proc: The MPS_RELEASE macro (see impl.c.version.release) is edited after making a release so that it contains the name of the next release to be made from the sources on that branch. For example, after making version 1.117, the source on the master branch is updated to say:

#define MPS_RELEASE "release/1.118.0"

and after making release 1.117.0, the source on the version/1.117 branch is updated to say:

#define MPS_RELEASE "release/1.117.1"

See the version creation and release build procedures respectively.

.impl.tool: The version string starts with the characters "@(#)". This is recognized by the standard Unix utility what(1). For example:

$ what mps.a
        Ravenbrook MPS, product.mps, release/1.117.0, platform.xci6ll, variety.asserted.logging.nonstats, compiled on Oct 18 2016 13:57:08