[dpdk-dev] [RFC PATCH 1/3] build: add a dpdk-specific meson log file

[Bruce Richardson <bruce.richardson@intel.com>]

While meson itself writes a log file of all the tests it runs and the
output of those, to help debug any build problems and provide more
developer information it can be helpful to have a logfile created and
controlled by the dpdk meson.build files themselves.

Since meson doesn't directly support this we need to use run_command to
implement it manually. Using a python script to do the writing of the log
makes things cross-platform, and as initial log entries we can add in the
messages about the defined internal dependencies, since these are of
developer interest only.

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 buildtools/meson.build        |  1 +
 buildtools/write-log-entry.py | 23 +++++++++++++++++++++++
 drivers/meson.build           |  2 +-
 lib/meson.build               |  2 +-
 meson.build                   |  8 ++++++--
 5 files changed, 32 insertions(+), 4 deletions(-)
 create mode 100644 buildtools/write-log-entry.py

diff --git a/buildtools/meson.build b/buildtools/meson.build
index 04808dabc..35a8f4290 100644
--- a/buildtools/meson.build
+++ b/buildtools/meson.build
@@ -17,3 +17,4 @@ else
 endif
 map_to_win_cmd = py3 + files('map_to_win.py')
 sphinx_wrapper = py3 + files('call-sphinx-build.py')
+log = py3 + [files('write-log-entry.py'), 'dpdk-meson.log']
diff --git a/buildtools/write-log-entry.py b/buildtools/write-log-entry.py
new file mode 100644
index 000000000..6ec748a4f
--- /dev/null
+++ b/buildtools/write-log-entry.py
@@ -0,0 +1,23 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2020 Intel Corporation
+
+from sys import argv, exit
+from time import strftime
+from os import environ
+from os.path import join as path_join
+
+if len(argv) < 2: # error if no filename
+    exit(1)
+if len(argv) < 3: # do nothing if no contents to log
+    exit(0)
+
+build_dir = environ.get('MESON_BUILD_ROOT', '.')
+filename = path_join(build_dir, argv[1])
+
+# append dates to headings
+if argv[2].startswith('===='):
+    argv.append(strftime('@@ %Y-%m-%d %X'))
+
+with open(filename, 'a') as log:
+    print(" ".join(argv[2:]), file=log)
diff --git a/drivers/meson.build b/drivers/meson.build
index a5a6fed06..c008abd4a 100644
--- a/drivers/meson.build
+++ b/drivers/meson.build
@@ -228,7 +228,7 @@ foreach subpath:subdirs
 			set_variable('shared_@0@'.format(lib_name), shared_dep)
 			set_variable('static_@0@'.format(lib_name), static_dep)
 			dependency_name = ''.join(lib_name.split('rte_'))
-			message('drivers/@0@: Defining dependency "@1@"'.format(
+			run_command(log, 'drivers/@0@: Defining dependency "@1@"'.format(
 					drv_path, dependency_name))
 		endif # build
 	endforeach
diff --git a/lib/meson.build b/lib/meson.build
index dd55b5cb5..2715c0f66 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -200,7 +200,7 @@ foreach l:libraries
 
 		set_variable('shared_rte_' + name, shared_dep)
 		set_variable('static_rte_' + name, static_dep)
-		message('lib/@0@: Defining dependency "@1@"'.format(
+		run_command(log, 'lib/@0@: Defining dependency "@1@"'.format(
 				dir_name, name))
 	endif # if build
 endforeach
diff --git a/meson.build b/meson.build
index 61d9a4f5f..ab950a2ce 100644
--- a/meson.build
+++ b/meson.build
@@ -11,6 +11,11 @@ project('DPDK', 'C',
 	meson_version: '>= 0.47.1'
 )
 
+# get tool paths and scripts
+subdir('buildtools')
+
+run_command(log, '======= Starting meson =======')
+
 # set up some global vars for compiler, platform, configuration, etc.
 cc = meson.get_compiler('c')
 dpdk_conf = configuration_data()
@@ -40,8 +45,7 @@ global_inc = include_directories('.', 'config',
 	'lib/librte_eal/@0@/include'.format(arch_subdir),
 )
 
-# do configuration and get tool paths
-subdir('buildtools')
+# do main build config
 subdir('config')
 
 # build libs and drivers
-- 
2.25.1