Use Path type in a few more places in neon_fixtures.py (#9018)

This is in preparation of replacing neon_fixtures.get_dir_size with
neon_fixtures.utils.get_dir_size() in next commit.

test_runner/fixtures/compare_fixtures.py

@@ -4,6 +4,7 @@ from abc import ABC, abstractmethod
 from contextlib import _GeneratorContextManager, contextmanager
 
 # Type-related stuff
+from pathlib import Path
 from typing import Dict, Iterator, List
 
 import pytest
@@ -229,11 +230,11 @@ class VanillaCompare(PgCompare):
         pass  # TODO find something
 
     def report_size(self):
-        data_size = self.pg.get_subdir_size("base")
+        data_size = self.pg.get_subdir_size(Path("base"))
         self.zenbenchmark.record(
             "data_size", data_size / (1024 * 1024), "MB", report=MetricReport.LOWER_IS_BETTER
         )
-        wal_size = self.pg.get_subdir_size("pg_wal")
+        wal_size = self.pg.get_subdir_size(Path("pg_wal"))
         self.zenbenchmark.record(
             "wal_size", wal_size / (1024 * 1024), "MB", report=MetricReport.LOWER_IS_BETTER
         )

test_runner/fixtures/neon_fixtures.py

@@ -224,7 +224,7 @@ def worker_base_port(worker_seq_no: int, worker_port_num: int) -> int:
     return BASE_PORT + worker_seq_no * worker_port_num
 
 
-def get_dir_size(path: str) -> int:
+def get_dir_size(path: Path) -> int:
     """Return size in bytes."""
     totalbytes = 0
     for root, _dirs, files in os.walk(path):
@@ -3319,12 +3319,12 @@ class PgBin:
         )
         return base_path
 
-    def get_pg_controldata_checkpoint_lsn(self, pgdata: str) -> Lsn:
+    def get_pg_controldata_checkpoint_lsn(self, pgdata: Path) -> Lsn:
         """
         Run pg_controldata on given datadir and extract checkpoint lsn.
         """
 
-        pg_controldata_path = os.path.join(self.pg_bin_path, "pg_controldata")
+        pg_controldata_path = self.pg_bin_path / "pg_controldata"
         cmd = f"{pg_controldata_path} -D {pgdata}"
         result = subprocess.run(cmd, capture_output=True, text=True, shell=True)
         checkpoint_lsn = re.findall(
@@ -3433,9 +3433,9 @@ class VanillaPostgres(PgProtocol):
         self.running = False
         self.pg_bin.run_capture(["pg_ctl", "-w", "-D", str(self.pgdatadir), "stop"])
 
-    def get_subdir_size(self, subdir) -> int:
+    def get_subdir_size(self, subdir: Path) -> int:
         """Return size of pgdatadir subdirectory in bytes."""
-        return get_dir_size(os.path.join(self.pgdatadir, subdir))
+        return get_dir_size(self.pgdatadir / subdir)
 
     def __enter__(self) -> "VanillaPostgres":
         return self
@@ -3962,7 +3962,7 @@ class Endpoint(PgProtocol, LogUtils):
         self.env = env
         self.branch_name: Optional[str] = None  # dubious
         self.endpoint_id: Optional[str] = None  # dubious, see asserts below
-        self.pgdata_dir: Optional[str] = None  # Path to computenode PGDATA
+        self.pgdata_dir: Optional[Path] = None  # Path to computenode PGDATA
         self.tenant_id = tenant_id
         self.pg_port = pg_port
         self.http_port = http_port
@@ -4019,7 +4019,7 @@ class Endpoint(PgProtocol, LogUtils):
             allow_multiple=allow_multiple,
         )
         path = Path("endpoints") / self.endpoint_id / "pgdata"
-        self.pgdata_dir = os.path.join(self.env.repo_dir, path)
+        self.pgdata_dir = self.env.repo_dir / path
         self.logfile = self.endpoint_path() / "compute.log"
 
         config_lines = config_lines or []
@@ -4072,21 +4072,21 @@ class Endpoint(PgProtocol, LogUtils):
         path = Path("endpoints") / self.endpoint_id
         return self.env.repo_dir / path
 
-    def pg_data_dir_path(self) -> str:
+    def pg_data_dir_path(self) -> Path:
         """Path to Postgres data directory"""
-        return os.path.join(self.endpoint_path(), "pgdata")
+        return self.endpoint_path() / "pgdata"
 
-    def pg_xact_dir_path(self) -> str:
+    def pg_xact_dir_path(self) -> Path:
         """Path to pg_xact dir"""
-        return os.path.join(self.pg_data_dir_path(), "pg_xact")
+        return self.pg_data_dir_path() / "pg_xact"
 
-    def pg_twophase_dir_path(self) -> str:
+    def pg_twophase_dir_path(self) -> Path:
         """Path to pg_twophase dir"""
-        return os.path.join(self.pg_data_dir_path(), "pg_twophase")
+        return self.pg_data_dir_path() / "pg_twophase"
 
-    def config_file_path(self) -> str:
+    def config_file_path(self) -> Path:
         """Path to the postgresql.conf in the endpoint directory (not the one in pgdata)"""
-        return os.path.join(self.endpoint_path(), "postgresql.conf")
+        return self.endpoint_path() / "postgresql.conf"
 
     def config(self, lines: List[str]) -> "Endpoint":
         """
@@ -4251,7 +4251,7 @@ class Endpoint(PgProtocol, LogUtils):
         log.info(f'checkpointing at LSN {self.safe_psql("select pg_current_wal_lsn()")[0][0]}')
         self.safe_psql("checkpoint")
         assert self.pgdata_dir is not None  # please mypy
-        return get_dir_size(os.path.join(self.pgdata_dir, "pg_wal")) / 1024 / 1024
+        return get_dir_size(self.pgdata_dir / "pg_wal") / 1024 / 1024
 
     def clear_shared_buffers(self, cursor: Optional[Any] = None):
         """