Correctly handle corrupted SMT models (#68)

machine/translation/thot/thot_smt_model.py

@@ -71,6 +71,10 @@ def __init__(
         else:
             self._config_filename = Path(config)
             parameters = ThotSmtParameters.load(config)
+        if not Path(parameters.translation_model_filename_prefix + ".ttable").is_file():
+            raise FileNotFoundError("The translation model could not be found.")
+        if not Path(parameters.language_model_filename_prefix).is_file():
+            raise FileNotFoundError("The language model could not be found.")
         self._parameters = parameters
         self.source_tokenizer = source_tokenizer
         self.target_tokenizer = target_tokenizer

machine/translation/thot/thot_utils.py

@@ -38,8 +38,10 @@ def load_smt_model(word_alignment_model_type: ThotWordAlignmentModelType, parame
         model_type = ta.AlignmentModelType.IBM4
 
     model = tt.SmtModel(model_type)
-    model.load_translation_model(parameters.translation_model_filename_prefix)
-    model.load_language_model(parameters.language_model_filename_prefix)
+    if not model.load_translation_model(parameters.translation_model_filename_prefix):
+        raise RuntimeError("Unable to load translation model.")
+    if not model.load_language_model(parameters.language_model_filename_prefix):
+        raise RuntimeError("Unable to load language model.")
     model.non_monotonicity = parameters.model_non_monotonicity
     model.w = parameters.model_w
     model.a = parameters.model_a

machine/translation/thot/thot_word_alignment_model.py

@@ -61,15 +61,16 @@ def load(self, prefix_filename: StrPath) -> None:
         prefix_filename = Path(prefix_filename)
         if not (prefix_filename.parent / (prefix_filename.name + ".src")).is_file():
             raise FileNotFoundError("The word alignment model configuration could not be found.")
-        self._prefix_filename = prefix_filename
         self._model.clear()
-        self._model.load(str(prefix_filename))
+        if not self._model.load(str(prefix_filename)):
+            raise RuntimeError("Unable to load word alignment model.")
+        self._prefix_filename = prefix_filename
 
     def create_new(self, prefix_filename: StrPath) -> None:
         if self._owned:
             raise RuntimeError("The word alignment model is owned by an SMT model.")
-        self._prefix_filename = Path(prefix_filename)
         self._model.clear()
+        self._prefix_filename = Path(prefix_filename)
 
     def save(self) -> None:
         if self._prefix_filename is not None:

pyproject.toml

@@ -60,7 +60,7 @@ charset-normalizer = "^2.1.1"
 
 ### extras
 sentencepiece = "^0.1.95"
-sil-thot = "^3.4.0"
+sil-thot = "^3.4.2"
 # huggingface extras
 transformers = "^4.34.0"
 datasets = "^2.4.0"

tests/corpora/test_text_file_text_corpus.py

@@ -1,11 +1,11 @@
-import pytest
+from pytest import raises
 from testutils.corpora_test_helpers import TEXT_TEST_PROJECT_PATH
 
 from machine.corpora import TextFileTextCorpus
 
 
 def test_does_not_exist() -> None:
-    with pytest.raises(FileNotFoundError):
+    with raises(FileNotFoundError):
         TextFileTextCorpus("does-not-exist.txt")
 
 

tests/jobs/test_nmt_engine_build_job.py

@@ -3,8 +3,8 @@
 from io import StringIO
 from typing import Iterator
 
-import pytest
 from decoy import Decoy, matchers
+from pytest import raises
 
 from machine.annotations import Range
 from machine.corpora import DictionaryTextCorpus
@@ -27,7 +27,7 @@ def test_run(decoy: Decoy) -> None:
 def test_cancel(decoy: Decoy) -> None:
     env = _TestEnvironment(decoy)
     checker = _CancellationChecker(3)
-    with pytest.raises(CanceledError):
+    with raises(CanceledError):
         env.job.run(check_canceled=checker.check_canceled)
 
     assert env.target_pretranslations == ""

tests/translation/thot/test_thot_fast_align_word_alignment_model.py

@@ -1,4 +1,7 @@
-from pytest import approx
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from pytest import approx, raises
 from testutils.thot_test_helpers import TOY_CORPUS_FAST_ALIGN_PATH
 
 from machine.translation import WordAlignmentMatrix
@@ -107,3 +110,11 @@ def test_get_avg_translation_score_symmetrized() -> None:
         matrix = model.align(source_segment, target_segment)
         score = model.get_avg_translation_score(source_segment, target_segment, matrix)
         assert score == approx(0.36, abs=0.01)
+
+
+def test_constructor_model_corrupted() -> None:
+    with TemporaryDirectory() as temp_dir:
+        temp_dir_path = Path(temp_dir)
+        (temp_dir_path / "src_trg_invswm.src").write_text("corrupted", encoding="utf-8")
+        with raises(RuntimeError):
+            ThotFastAlignWordAlignmentModel(temp_dir_path / "src_trg_invswm")

tests/translation/thot/test_thot_smt_model.py

@@ -1,6 +1,10 @@
+from pathlib import Path
+from tempfile import TemporaryDirectory
+
+from pytest import raises
 from testutils.thot_test_helpers import TOY_CORPUS_FAST_ALIGN_CONFIG_FILENAME, TOY_CORPUS_HMM_CONFIG_FILENAME
 
-from machine.translation.thot import ThotSmtModel, ThotWordAlignmentModelType
+from machine.translation.thot import ThotSmtModel, ThotSmtParameters, ThotWordAlignmentModelType
 
 
 def test_translate_target_segment_hmm() -> None:
@@ -95,6 +99,35 @@ def test_get_word_graph_empty_segment_fast_align() -> None:
         assert word_graph.is_empty
 
 
+def test_constructor_model_not_found() -> None:
+    with raises(FileNotFoundError):
+        ThotSmtModel(
+            ThotWordAlignmentModelType.HMM,
+            ThotSmtParameters(
+                translation_model_filename_prefix="does-not-exist", language_model_filename_prefix="does-not-exist"
+            ),
+        )
+
+
+def test_constructor_model_corrupted() -> None:
+    with TemporaryDirectory() as temp_dir:
+        temp_dir_path = Path(temp_dir)
+        tm_dir_path = temp_dir_path / "tm"
+        tm_dir_path.mkdir()
+        (tm_dir_path / "src_trg.ttable").write_text("corrupted", encoding="utf-8")
+        lm_dir_path = temp_dir_path / "lm"
+        lm_dir_path.mkdir()
+        (lm_dir_path / "trg.lm").write_text("corrupted", encoding="utf-8")
+        with raises(RuntimeError):
+            ThotSmtModel(
+                ThotWordAlignmentModelType.HMM,
+                ThotSmtParameters(
+                    translation_model_filename_prefix=str(tm_dir_path / "src_trg"),
+                    language_model_filename_prefix=str(lm_dir_path / "trg.lm"),
+                ),
+            )
+
+
 def _create_hmm_model() -> ThotSmtModel:
     return ThotSmtModel(ThotWordAlignmentModelType.HMM, TOY_CORPUS_HMM_CONFIG_FILENAME)