[PATCH v4 2/8] build: output a dependency log in build directory

[Anatoly Burakov <anatoly.burakov@intel.com>]

From: Bruce Richardson <bruce.richardson@intel.com>

As meson processes our DPDK source tree it manages dependencies
specified by each individual driver. To enable future analysis of the
dependency links between components, log the dependencies of each DPDK
component as it gets processed. This could potentially allow other tools
to automatically enable or disable components based on the desired end
components to be built, e.g. if the user requests net/ice, ensure that
common/iavf is also enabled in the drivers.

The output file produced is in "dot" or "graphviz" format, which allows
producing a graphical representation of the DPDK dependency tree if so
desired. For example: "dot -Tpng -O build/deps.dot" to produce the
image file "build/deps.dot.png".

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
Acked-by: Konstantin Ananyev <konstantin.ananyev@huawei.com>
Signed-off-by: Anatoly Burakov <anatoly.burakov@intel.com>
---
 app/meson.build        |  8 ++++-
 buildtools/log-deps.py | 81 ++++++++++++++++++++++++++++++++++++++++++
 buildtools/meson.build |  2 ++
 drivers/meson.build    |  6 ++++
 examples/meson.build   |  8 ++++-
 lib/meson.build        |  5 +++
 6 files changed, 108 insertions(+), 2 deletions(-)
 create mode 100644 buildtools/log-deps.py

diff --git a/app/meson.build b/app/meson.build
index 4e88e652ca..a770fed802 100644
--- a/app/meson.build
+++ b/app/meson.build
@@ -76,8 +76,14 @@ foreach app:apps
         reason = 'explicitly disabled via build config'
     endif
 
+    app_name = 'dpdk-' + name
     if build
         subdir(name)
+        type_cmd = '--type=app'
+        run_command([log_deps_cmd, type_cmd, app_name, deps], check: false)
+        if optional_deps.length() > 0
+            run_command([log_deps_cmd, '--optional', type_cmd, app_name, optional_deps], check: false)
+        endif
         if not build and require_apps
             error('Cannot build explicitly requested app "@0@".\n'.format(name)
                   + '\tReason: ' + reason)
@@ -116,7 +122,7 @@ foreach app:apps
         link_libs = dpdk_static_libraries + dpdk_drivers
     endif
 
-    exec = executable('dpdk-' + name,
+    exec = executable(app_name,
             [ sources, resources ],
             c_args: cflags,
             link_args: ldflags,
diff --git a/buildtools/log-deps.py b/buildtools/log-deps.py
new file mode 100644
index 0000000000..e11a102242
--- /dev/null
+++ b/buildtools/log-deps.py
@@ -0,0 +1,81 @@
+#! /usr/bin/env python3
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2024 Intel Corporation
+
+"""Utility script to build up a list of dependencies from meson."""
+
+import os
+import sys
+import argparse
+import typing as T
+
+
+def file_to_list(filename: str) -> T.List[str]:
+    """Read file into a list of strings."""
+    with open(filename, encoding="utf-8") as f:
+        return f.readlines()
+
+
+def list_to_file(filename: str, lines: T.List[str]):
+    """Write a list of strings out to a file."""
+    with open(filename, "w", encoding="utf-8") as f:
+        f.writelines(lines)
+
+
+def gen_deps(
+    component_type: str, optional: bool, component: str, deps: T.List[str]
+) -> str:
+    """Generate a dependency graph for meson."""
+    dep_list_str = '", "'.join(deps)
+    deps_str = "" if not deps else f' -> {{ "{dep_list_str}" }}'
+    # we define custom attributes for the nodes
+    attr_str = f'dpdk_componentType="{component_type}"'
+    if optional:
+        # we use a dotted line to represent optional dependencies
+        attr_str += ',style="dotted"'
+    return f'"{component}"{deps_str} [{attr_str}]\n'
+
+
+def _main():
+    depsfile = f'{os.environ["MESON_BUILD_ROOT"]}/deps.dot'
+
+    # to reset the deps file on each build, the script is called without any params
+    if len(sys.argv) == 1:
+        os.remove(depsfile)
+        sys.exit(0)
+
+    # we got arguments, parse them
+    parser = argparse.ArgumentParser(
+        description="Generate a dependency graph for meson."
+    )
+    # type is required
+    parser.add_argument(
+        "--type", required=True, help="Type of dependency (lib, examples, etc.)"
+    )
+    parser.add_argument(
+        "--optional", action="store_true", help="Whether the dependency is optional"
+    )
+    # component is required
+    parser.add_argument("component", help="The component to add to the graph")
+    parser.add_argument("deps", nargs="*", help="The dependencies of the component")
+
+    parsed = parser.parse_args()
+
+    try:
+        contents = file_to_list(depsfile)
+    except FileNotFoundError:
+        contents = ["digraph {\n", "}\n"]
+
+    c_type = parsed.type
+    optional = parsed.optional
+    component = parsed.component
+    deps = parsed.deps
+    contents[-1] = gen_deps(c_type, optional, component, deps)
+
+    contents.append("}\n")
+
+    list_to_file(depsfile, contents)
+
+
+if __name__ == "__main__":
+    _main()
diff --git a/buildtools/meson.build b/buildtools/meson.build
index 4e2c1217a2..13a0477245 100644
--- a/buildtools/meson.build
+++ b/buildtools/meson.build
@@ -26,6 +26,8 @@ header_gen_cmd = py3 + files('gen-header.py')
 has_hugepages_cmd = py3 + files('has-hugepages.py')
 cmdline_gen_cmd = py3 + files('dpdk-cmdline-gen.py')
 check_dts_requirements = py3 + files('check-dts-requirements.py')
+log_deps_cmd = py3 + files('log-deps.py')
+run_command(log_deps_cmd, check: false)  # call with no parameters to reset the file
 
 # install any build tools that end-users might want also
 install_data([
diff --git a/drivers/meson.build b/drivers/meson.build
index 7a144cc527..338efe42b8 100644
--- a/drivers/meson.build
+++ b/drivers/meson.build
@@ -159,6 +159,12 @@ foreach subpath:subdirs
         if build
             # pull in driver directory which should update all the local variables
             subdir(drv_path)
+            type_cmd = '--type=drivers'
+            drv_name = class + '_' + name
+            run_command([log_deps_cmd, type_cmd, drv_name, deps], check: false)
+            if optional_deps.length() > 0
+                run_command([log_deps_cmd, '--optional', type_cmd, drv_name, optional_deps], check: false)
+            endif
 
             if dpdk_conf.get('RTE_IOVA_IN_MBUF') == 0 and require_iova_in_mbuf
                 build = false
diff --git a/examples/meson.build b/examples/meson.build
index 82151d09b4..1589a3057e 100644
--- a/examples/meson.build
+++ b/examples/meson.build
@@ -101,8 +101,14 @@ foreach example: examples
     optional_deps = []
     subdir(example)
 
+    example_name = 'dpdk-' + name
     if build
         dep_objs = ext_deps
+        type_cmd = '--type=examples'
+        run_command([log_deps_cmd, type_cmd, example_name, deps], check: false)
+        if optional_deps.length() > 0
+            run_command([log_deps_cmd, '--optional', type_cmd, example_name, optional_deps], check: false)
+        endif
         foreach d:deps + optional_deps
             var_name = get_option('default_library') + '_rte_' + d
             if not is_variable(var_name)
@@ -125,7 +131,7 @@ foreach example: examples
     if allow_experimental_apis
         cflags += '-DALLOW_EXPERIMENTAL_API'
     endif
-    executable('dpdk-' + name, sources,
+    executable(example_name, sources,
             include_directories: includes,
             link_whole: link_whole_libs,
             link_args: ldflags,
diff --git a/lib/meson.build b/lib/meson.build
index 82ad5dba67..d1d772d4f4 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -161,6 +161,11 @@ foreach l:libraries
 
     if build
         subdir(l)
+        type_cmd = '--type=lib'
+        run_command([log_deps_cmd, type_cmd, l, deps], check: false)
+        if optional_deps.length() > 0
+            run_command([log_deps_cmd, '--optional', type_cmd, l, optional_deps], check: false)
+        endif
         if not build and require_libs
             error('Cannot build explicitly requested lib "@0@".\n'.format(name)
                     +'\tReason: ' + reason)
-- 
2.43.5