Plug http retriever in current logic

- Do not use lambda
 - Replace assert with raise
 - Minor fixes

techrec/forge.py

@@ -7,19 +7,25 @@ from time import sleep
 from typing import Callable, Optional
 
 from .config_manager import get_config
+from .http_retriever import RETRIEVER
 
 logger = logging.getLogger("forge")
 Validator = Callable[[datetime, datetime, str], bool]
 
 
-def get_timefile_exact(time) -> str:
+async def get_timefile_exact(time) -> str:
     """
     time is of type `datetime`; it is not "rounded" to match the real file;
     that work is done in get_timefile(time)
     """
-    return os.path.join(
-        get_config()["AUDIO_INPUT"], time.strftime(get_config()["AUDIO_INPUT_FORMAT"])
+    remote_repo = get_config()["AUDIO_INPUT"]
+    remote_path = os.path.join(
+        remote_repo, time.strftime(get_config()["AUDIO_INPUT_FORMAT"])
     )
+    if remote.startswith("http"):
+        local = await RETRIEVER.get(remote_path)
+        return local
+    return local_path
 
 
 def round_timefile(exact: datetime) -> datetime:
@@ -29,8 +35,9 @@ def round_timefile(exact: datetime) -> datetime:
     return datetime(exact.year, exact.month, exact.day, exact.hour)
 
 
-def get_timefile(exact: datetime) -> str:
-    return get_timefile_exact(round_timefile(exact))
+async def get_timefile(exact: datetime) -> str:
+    file = await get_timefile_exact(round_timefile(exact))
+    return file
 
 
 def get_files_and_intervals(start, end, rounder=round_timefile):
@@ -70,13 +77,16 @@ def mp3_join(named_intervals):
     for (filename, start_cut, end_cut) in named_intervals:
         # this happens only one time, and only at the first iteration
         if start_cut:
-            assert startskip is None
+            if startskip is not None:
+                raise Exception("error in first cut iteration")
             startskip = start_cut
-        # this happens only one time, and only at the first iteration
+        # this happens only one time, and only at the last iteration
         if end_cut:
-            assert endskip is None
+            if endskip is not None:
+                raise Exception("error in last iteration")
             endskip = end_cut
-        assert "|" not in filename
+        if "|" in filename:
+            raise Exception(f"'|' in {filename}")
         files.append(filename)
 
     cmdline = [ffmpeg, "-i", "concat:%s" % "|".join(files)]
@@ -90,20 +100,23 @@ def mp3_join(named_intervals):
     return cmdline
 
 
-def create_mp3(
+async def create_mp3(
     start: datetime,
     end: datetime,
     outfile: str,
     options={},
     validator: Optional[Validator] = None,
-    **kwargs
+    **kwargs,
 ):
     if validator is None:
-        validator = lambda s, e, f: True
-    intervals = [
-        (get_timefile(begin), start_cut, end_cut)
-        for begin, start_cut, end_cut in get_files_and_intervals(start, end)
-    ]
+
+        def validator(s, e, f):
+            return True
+
+    intervals = []
+    for begin, start_cut, end_cut in get_files_and_intervals(start, end):
+        file = await get_timefile(begin)
+        interval.append(file, start_cut, end_cut)
     if os.path.exists(outfile):
         raise OSError("file '%s' already exists" % outfile)
     for path, _s, _e in intervals:
@@ -162,7 +175,7 @@ def create_mp3(
         os.kill(p.pid, 15)
         try:
             os.remove(tmp_file.name)
-        except:
+        except Exception:
             pass
         raise Exception("timeout")  # TODO: make a specific TimeoutError
     if p.returncode != 0:
@@ -174,8 +187,8 @@ def create_mp3(
     return True
 
 
-def main_cmd(options):
+async def main_cmd(options):
     log = logging.getLogger("forge_main")
     outfile = os.path.abspath(os.path.join(options.cwd, options.outfile))
     log.debug("will forge an mp3 into %s" % (outfile))
-    create_mp3(options.starttime, options.endtime, outfile)
+    await create_mp3(options.starttime, options.endtime, outfile)

techrec/http_retriever.py

@@ -0,0 +1,60 @@
+# -*- encoding: utf-8 -*-
+import asyncio
+import os
+
+import aiohttp  # type: ignore
+
+from .config_manager import get_config
+
+CHUNK_SIZE = 2 ** 12
+
+
+class HTTPRetriever(object):
+    """
+    This class offers the `get` method to retrieve the file from the local staging path
+    or, if missing, from the given remote.
+    """
+    _instance = None
+
+    def __new__(cls):
+        if self._instance is None:
+            self._instance = super().__new__(cls)
+        return self._instance
+
+    def __init__(self):
+        self.repo_path = get_config()["AUDIO_STAGING"]
+        self.repo = dict(
+            path=os.path.join(self.repo_path, path) for i in os.listdir(self.repo_path)
+        )
+
+    async def get(remote: str) -> str:
+        """
+        This will look in the local staging path (ideally on a tmpfs or something
+        similar), and return the file from there if present. Otherwise, it will download
+        it from the remote.
+        """
+        if remote in self.repo:
+            return self.repo[remote]
+        file = await self._download_from_remote(remote)
+        self.repo[] = file
+        return file
+
+    async def _download(remote: str) -> str:
+        """
+        This will download to AUDIO_STAGING the remote file and return the local path
+        of the downloaded file
+        """
+        _, filename = os.path.split(remote)
+        local = os.path.join(get_config()["AUDIO_STAGING"], filename)
+        async with aiohttp.ClientSession() as session:
+            async with session.get(remote) as resp:
+                with open(local) as f:
+                    while True:
+                        chunk = await resp.content.read(CHUNK_SIZE)
+                        if not chunk:
+                            break
+                        f.write(chunk)
+        return local
+
+
+RETRIEVER = HTTPRetriever()

techrec/server.py

@@ -256,7 +256,7 @@ def get_validator(expected_duration_s: float, error_threshold_s: float) -> Valid
     return validator
 
 
-def generate_mp3(db_id: int, **kwargs):
+async def generate_mp3(db_id: int, **kwargs):
     """creates and mark it as ready in the db"""
     if get_config()["FORGE_VERIFY"]:
         validator = get_validator(
@@ -269,7 +269,7 @@ def generate_mp3(db_id: int, **kwargs):
         retries = 1
 
     for i in range(retries):
-        result = create_mp3(validator=validator, **kwargs)
+        result = await create_mp3(validator=validator, **kwargs)
         logger.debug("Create mp3 for %d -> %s", db_id, result)
         if result:
             break