Use a dataclass for "branches"

master/custom/__init__.py

@@ -1,5 +1 @@
-MAIN_BRANCH_VERSION = "3.15"
-# The Git branch is called "main", but we give it a different name in buildbot.
-# See git_branches in master/master.cfg.
-MAIN_BRANCH_NAME = "3.x"
 JUNIT_FILENAME = "test-results.xml"

master/custom/branches.py

@@ -0,0 +1,134 @@
+"""All the info about Buildbot branches
+
+We treat the main branch specially, and we use a pseudo-branch for the
+Pull Request buildbots.
+In older branches some config needs to be nudged -- for example,
+free-threading builds only make sense in 3.13+.
+
+Complex enough to wrap up in a dataclass: BranchInfo.
+
+
+Run this as a CLI command to print the info out:
+
+    python master/custom/branches.py
+
+"""
+
+import dataclasses
+from functools import total_ordering
+from typing import Any
+
+# Buildbot configuration first; see below for the BranchInfo class.
+
+def generate_branches():
+    yield BranchInfo(
+        'main',
+        version_tuple=(3, 15),
+        git_ref='main',
+        is_main=True,
+        builddir_name='main',
+        builder_tag='main',
+        sort_key=-9999,
+    )
+    yield _maintenance_branch(3, 14)
+    yield _maintenance_branch(3, 13)
+    yield _maintenance_branch(3, 12)
+    yield _maintenance_branch(3, 11)
+    yield _maintenance_branch(3, 10)
+    yield BranchInfo(
+        'PR',
+        version_tuple=None,
+        git_ref=None,
+        is_pr=True,
+        builddir_name='pull_request',
+        builder_tag='PullRequest',
+        sort_key=0,
+    )
+
+
+def _maintenance_branch(major, minor, **kwargs):
+    version_tuple = (major, minor)
+    version_str = f'{major}.{minor}'
+    result = BranchInfo(
+        name=version_str,
+        builder_tag=version_str,
+        version_tuple=version_tuple,
+        git_ref=version_str,
+        builddir_name=version_str,
+        sort_key=-minor,
+    )
+
+    if version_tuple < (3, 11):
+        # Before 3.11, test_asyncio wasn't split out, and refleaks tests
+        # need more time.
+        result.monolithic_test_asyncio = True
+
+    if version_tuple < (3, 11):
+        # WASM wasn't a supported platform until 3.11.
+        result.wasm_tier = None
+    elif version_tuple < (3, 13):
+        # Tier 3 support is 3.11 & 3.12.
+        result.wasm_tier = 3
+
+    if version_tuple < (3, 13):
+        # Free-threaded builds are available since 3.13
+        result.gil_only = True
+
+    return result
+
+
+@total_ordering
+@dataclasses.dataclass
+class BranchInfo:
+    name: str
+    version_tuple: tuple[int, int] | None
+    git_ref: str | None
+    builddir_name: str
+    builder_tag: str
+
+    sort_key: Any
+
+    is_main: bool = False
+    is_pr: bool = False
+
+    # Branch features.
+    # Defaults are for main (and PR), overrides are in _maintenance_branch.
+    gil_only: bool = False
+    monolithic_test_asyncio: bool = False
+    wasm_tier: int | None = 2
+
+    def __str__(self):
+        return self.name
+
+    def __eq__(self, other):
+        try:
+            other_key = other.sort_key
+        except AttributeError:
+            return NotImplemented
+        return self.sort_key == other.sort_key
+
+    def __lt__(self, other):
+        try:
+            other_key = other.sort_key
+        except AttributeError:
+            return NotImplemented
+        return self.sort_key < other.sort_key
+
+
+BRANCHES = list(generate_branches())
+PR_BRANCH = BRANCHES[-1]
+
+# Verify that we've defined these in sort order
+assert BRANCHES == sorted(BRANCHES)
+
+if __name__ == "__main__":
+    # Print a table to the terminal
+    cols = [[f.name + ':' for f in dataclasses.fields(BranchInfo)]]
+    for branch in BRANCHES:
+        cols.append([repr(val) for val in dataclasses.astuple(branch)])
+    column_sizes = [max(len(val) for val in col) for col in cols]
+    column_sizes[-2] += 2  # PR is special, offset it a bit
+    for row in zip(*cols):
+        for size, val in zip(column_sizes, row):
+            print(val.ljust(size), end=' ')
+        print()

master/custom/factories.py

@@ -9,8 +9,7 @@
 
 from buildbot.plugins import util
 
-from . import (MAIN_BRANCH_VERSION, MAIN_BRANCH_NAME,
-               JUNIT_FILENAME)
+from . import JUNIT_FILENAME
 from .steps import (
     Test,
     Clean,
@@ -56,6 +55,8 @@ def get_j_opts(worker, default=None):
 class BaseBuild(factory.BuildFactory):
     factory_tags = []
     test_timeout = TEST_TIMEOUT
+    buildersuffix = ""
+    tags = ()
 
     def __init__(self, source, *, extra_tags=[], **kwargs):
         super().__init__([source])
@@ -97,7 +98,7 @@ def setup(self, branch, worker, test_with_PTY=False, **kwargs):
 
         # In 3.10, test_asyncio wasn't split out, and refleaks tests
         # need more time.
-        if branch == "3.10" and has_option("-R", self.testFlags):
+        if branch.monolithic_test_asyncio and has_option("-R", self.testFlags):
             self.test_timeout *= 2
 
         if self.build_out_of_tree:
@@ -161,7 +162,7 @@ def setup(self, branch, worker, test_with_PTY=False, **kwargs):
             env=self.test_environ,
             **oot_kwargs
         ))
-        if branch not in ("3",) and not has_option("-R", self.testFlags):
+        if not branch.is_pr and not has_option("-R", self.testFlags):
             filename = JUNIT_FILENAME
             if self.build_out_of_tree:
                 filename = os.path.join(out_of_tree_dir, filename)
@@ -214,11 +215,12 @@ class UnixInstalledBuild(BaseBuild):
     factory_tags = ["installed"]
 
     def setup(self, branch, worker, test_with_PTY=False, **kwargs):
-        if branch == MAIN_BRANCH_NAME:
-            branch = MAIN_BRANCH_VERSION
-        elif branch == "custom":
-            branch = "3"
-        installed_python = f"./target/bin/python{branch}"
+        if branch.version_tuple:
+            major, minor = branch.version_tuple
+            executable_name = f'python{major}.{minor}'
+        else:
+            executable_name = f'python3'
+        installed_python = f"./target/bin/{executable_name}"
         self.addStep(
             Configure(
                 command=["./configure", "--prefix", "$(PWD)/target"]
@@ -633,7 +635,7 @@ def setup(self, branch, worker, **kwargs):
             command=test_command,
             timeout=step_timeout(self.test_timeout),
         ))
-        if branch not in ("3",) and not has_option("-R", self.testFlags):
+        if not branch.is_pr and not has_option("-R", self.testFlags):
             self.addStep(UploadTestResults(branch))
         self.addStep(Clean(command=clean_command))
 
@@ -856,7 +858,7 @@ def setup(self, branch, worker, test_with_PTY=False, **kwargs):
                 env=self.test_environ,
                 workdir=oot_host_path,
             ))
-            if branch not in ("3",) and not has_option("-R", self.testFlags):
+            if not branch.is_pr and not has_option("-R", self.testFlags):
                 filename = os.path.join(oot_host_path, JUNIT_FILENAME)
                 self.addStep(UploadTestResults(branch, filename=filename))
         self.addStep(
@@ -990,7 +992,7 @@ def setup(self, branch, worker, test_with_PTY=False, **kwargs):
                 workdir=host_path,
             )
         )
-        if branch not in ("3",) and not has_option("-R", self.testFlags):
+        if not branch.is_pr and not has_option("-R", self.testFlags):
             filename = os.path.join(host_path, JUNIT_FILENAME)
             self.addStep(UploadTestResults(branch, filename=filename))
 
@@ -1240,7 +1242,7 @@ def setup(self, branch, *args, **kwargs):
         #
         # The symlink approach will fail for Python 3.13 *PR* builds, because
         # there's no way to identify the base branch for a PR.
-        if branch == "3.13":
+        if branch.name == "3.13":
             self.py313_setup(branch, *args, **kwargs)
         else:
             self.current_setup(branch, *args, **kwargs)

master/custom/workers.py

@@ -8,7 +8,6 @@
 
 from buildbot.plugins import worker as _worker
 
-from custom.factories import MAIN_BRANCH_NAME
 from custom.worker_downtime import no_builds_between