import logging
import re
import string
import threading
from concurrent.futures import ThreadPoolExecutor, wait
from typing import Any, Dict, List, Literal, Optional, Tuple
from langchain_core._api.deprecation import deprecated
from langchain_core.embeddings import Embeddings
from langchain_core.language_models.llms import create_base_retry_decorator
from langchain_core.utils import pre_init
from langchain_community.llms.vertexai import _VertexAICommon
from langchain_community.utilities.vertexai import raise_vertex_import_error
logger = logging.getLogger(__name__)
_MAX_TOKENS_PER_BATCH = 20000
_MAX_BATCH_SIZE = 250
_MIN_BATCH_SIZE = 5
[docs]
@deprecated(
since="0.0.12",
removal="1.0",
alternative_import="langchain_google_vertexai.VertexAIEmbeddings",
)
class VertexAIEmbeddings(_VertexAICommon, Embeddings): # type: ignore[override]
"""Google Cloud VertexAI embedding models."""
# Instance context
instance: Dict[str, Any] = {} #: :meta private:
show_progress_bar: bool = False
"""Whether to show a tqdm progress bar. Must have `tqdm` installed."""
[docs]
@pre_init
def validate_environment(cls, values: Dict) -> Dict:
"""Validates that the python package exists in environment."""
cls._try_init_vertexai(values)
if values["model_name"] == "textembedding-gecko-default":
logger.warning(
"Model_name will become a required arg for VertexAIEmbeddings "
"starting from Feb-01-2024. Currently the default is set to "
"textembedding-gecko@001"
)
values["model_name"] = "textembedding-gecko@001"
try:
from vertexai.language_models import TextEmbeddingModel
except ImportError:
raise_vertex_import_error()
values["client"] = TextEmbeddingModel.from_pretrained(values["model_name"])
return values
def __init__(
self,
# the default value would be removed after Feb-01-2024
model_name: str = "textembedding-gecko-default",
project: Optional[str] = None,
location: str = "us-central1",
request_parallelism: int = 5,
max_retries: int = 6,
credentials: Optional[Any] = None,
**kwargs: Any,
):
"""Initialize the sentence_transformer."""
super().__init__(
project=project,
location=location,
credentials=credentials,
request_parallelism=request_parallelism,
max_retries=max_retries,
model_name=model_name,
**kwargs,
)
self.instance["max_batch_size"] = kwargs.get("max_batch_size", _MAX_BATCH_SIZE)
self.instance["batch_size"] = self.instance["max_batch_size"]
self.instance["min_batch_size"] = kwargs.get("min_batch_size", _MIN_BATCH_SIZE)
self.instance["min_good_batch_size"] = self.instance["min_batch_size"]
self.instance["lock"] = threading.Lock()
self.instance["batch_size_validated"] = False
self.instance["task_executor"] = ThreadPoolExecutor(
max_workers=request_parallelism
)
self.instance[
"embeddings_task_type_supported"
] = not self.client._endpoint_name.endswith("/textembedding-gecko@001")
@staticmethod
def _split_by_punctuation(text: str) -> List[str]:
"""Splits a string by punctuation and whitespace characters."""
split_by = string.punctuation + "\t\n "
pattern = f"([{split_by}])"
# Using re.split to split the text based on the pattern
return [segment for segment in re.split(pattern, text) if segment]
@staticmethod
def _prepare_batches(texts: List[str], batch_size: int) -> List[List[str]]:
"""Splits texts in batches based on current maximum batch size
and maximum tokens per request.
"""
text_index = 0
texts_len = len(texts)
batch_token_len = 0
batches: List[List[str]] = []
current_batch: List[str] = []
if texts_len == 0:
return []
while text_index < texts_len:
current_text = texts[text_index]
# Number of tokens per a text is conservatively estimated
# as 2 times number of words, punctuation and whitespace characters.
# Using `count_tokens` API will make batching too expensive.
# Utilizing a tokenizer, would add a dependency that would not
# necessarily be reused by the application using this class.
current_text_token_cnt = (
len(VertexAIEmbeddings._split_by_punctuation(current_text)) * 2
)
end_of_batch = False
if current_text_token_cnt > _MAX_TOKENS_PER_BATCH:
# Current text is too big even for a single batch.
# Such request will fail, but we still make a batch
# so that the app can get the error from the API.
if len(current_batch) > 0:
# Adding current batch if not empty.
batches.append(current_batch)
current_batch = [current_text]
text_index += 1
end_of_batch = True
elif (
batch_token_len + current_text_token_cnt > _MAX_TOKENS_PER_BATCH
or len(current_batch) == batch_size
):
end_of_batch = True
else:
if text_index == texts_len - 1:
# Last element - even though the batch may be not big,
# we still need to make it.
end_of_batch = True
batch_token_len += current_text_token_cnt
current_batch.append(current_text)
text_index += 1
if end_of_batch:
batches.append(current_batch)
current_batch = []
batch_token_len = 0
return batches
def _get_embeddings_with_retry(
self, texts: List[str], embeddings_type: Optional[str] = None
) -> List[List[float]]:
"""Makes a Vertex AI model request with retry logic."""
from google.api_core.exceptions import (
Aborted,
DeadlineExceeded,
ResourceExhausted,
ServiceUnavailable,
)
errors = [
ResourceExhausted,
ServiceUnavailable,
Aborted,
DeadlineExceeded,
]
retry_decorator = create_base_retry_decorator(
error_types=errors, # type: ignore[arg-type]
max_retries=self.max_retries, # type: ignore[arg-type]
)
@retry_decorator
def _completion_with_retry(texts_to_process: List[str]) -> Any:
if embeddings_type and self.instance["embeddings_task_type_supported"]:
from vertexai.language_models import TextEmbeddingInput
requests = [
TextEmbeddingInput(text=t, task_type=embeddings_type)
for t in texts_to_process
]
else:
requests = texts_to_process
embeddings = self.client.get_embeddings(requests)
return [embs.values for embs in embeddings]
return _completion_with_retry(texts)
def _prepare_and_validate_batches(
self, texts: List[str], embeddings_type: Optional[str] = None
) -> Tuple[List[List[float]], List[List[str]]]:
"""Prepares text batches with one-time validation of batch size.
Batch size varies between GCP regions and individual project quotas.
# Returns embeddings of the first text batch that went through,
# and text batches for the rest of the texts.
"""
from google.api_core.exceptions import InvalidArgument
batches = VertexAIEmbeddings._prepare_batches(
texts, self.instance["batch_size"]
)
# If batch size if less or equal to one that went through before,
# then keep batches as they are.
if len(batches[0]) <= self.instance["min_good_batch_size"]:
return [], batches
with self.instance["lock"]:
# If largest possible batch size was validated
# while waiting for the lock, then check for rebuilding
# our batches, and return.
if self.instance["batch_size_validated"]:
if len(batches[0]) <= self.instance["batch_size"]:
return [], batches
else:
return [], VertexAIEmbeddings._prepare_batches(
texts, self.instance["batch_size"]
)
# Figure out largest possible batch size by trying to push
# batches and lowering their size in half after every failure.
first_batch = batches[0]
first_result = []
had_failure = False
while True:
try:
first_result = self._get_embeddings_with_retry(
first_batch, embeddings_type
)
break
except InvalidArgument:
had_failure = True
first_batch_len = len(first_batch)
if first_batch_len == self.instance["min_batch_size"]:
raise
first_batch_len = max(
self.instance["min_batch_size"], int(first_batch_len / 2)
)
first_batch = first_batch[:first_batch_len]
first_batch_len = len(first_batch)
self.instance["min_good_batch_size"] = max(
self.instance["min_good_batch_size"], first_batch_len
)
# If had a failure and recovered
# or went through with the max size, then it's a legit batch size.
if had_failure or first_batch_len == self.instance["max_batch_size"]:
self.instance["batch_size"] = first_batch_len
self.instance["batch_size_validated"] = True
# If batch size was updated,
# rebuild batches with the new batch size
# (texts that went through are excluded here).
if first_batch_len != self.instance["max_batch_size"]:
batches = VertexAIEmbeddings._prepare_batches(
texts[first_batch_len:], self.instance["batch_size"]
)
else:
# Still figuring out max batch size.
batches = batches[1:]
# Returning embeddings of the first text batch that went through,
# and text batches for the rest of texts.
return first_result, batches
[docs]
def embed(
self,
texts: List[str],
batch_size: int = 0,
embeddings_task_type: Optional[
Literal[
"RETRIEVAL_QUERY",
"RETRIEVAL_DOCUMENT",
"SEMANTIC_SIMILARITY",
"CLASSIFICATION",
"CLUSTERING",
]
] = None,
) -> List[List[float]]:
"""Embed a list of strings.
Args:
texts: List[str] The list of strings to embed.
batch_size: [int] The batch size of embeddings to send to the model.
If zero, then the largest batch size will be detected dynamically
at the first request, starting from 250, down to 5.
embeddings_task_type: [str] optional embeddings task type,
one of the following
RETRIEVAL_QUERY - Text is a query
in a search/retrieval setting.
RETRIEVAL_DOCUMENT - Text is a document
in a search/retrieval setting.
SEMANTIC_SIMILARITY - Embeddings will be used
for Semantic Textual Similarity (STS).
CLASSIFICATION - Embeddings will be used for classification.
CLUSTERING - Embeddings will be used for clustering.
Returns:
List of embeddings, one for each text.
"""
if len(texts) == 0:
return []
embeddings: List[List[float]] = []
first_batch_result: List[List[float]] = []
if batch_size > 0:
# Fixed batch size.
batches = VertexAIEmbeddings._prepare_batches(texts, batch_size)
else:
# Dynamic batch size, starting from 250 at the first call.
first_batch_result, batches = self._prepare_and_validate_batches(
texts, embeddings_task_type
)
# First batch result may have some embeddings already.
# In such case, batches have texts that were not processed yet.
embeddings.extend(first_batch_result)
tasks = []
if self.show_progress_bar:
try:
from tqdm import tqdm
iter_ = tqdm(batches, desc="VertexAIEmbeddings")
except ImportError:
logger.warning(
"Unable to show progress bar because tqdm could not be imported. "
"Please install with `pip install tqdm`."
)
iter_ = batches
else:
iter_ = batches
for batch in iter_:
tasks.append(
self.instance["task_executor"].submit(
self._get_embeddings_with_retry,
texts=batch,
embeddings_type=embeddings_task_type,
)
)
if len(tasks) > 0:
wait(tasks)
for t in tasks:
embeddings.extend(t.result())
return embeddings
[docs]
def embed_documents(
self, texts: List[str], batch_size: int = 0
) -> List[List[float]]:
"""Embed a list of documents.
Args:
texts: List[str] The list of texts to embed.
batch_size: [int] The batch size of embeddings to send to the model.
If zero, then the largest batch size will be detected dynamically
at the first request, starting from 250, down to 5.
Returns:
List of embeddings, one for each text.
"""
return self.embed(texts, batch_size, "RETRIEVAL_DOCUMENT")
[docs]
def embed_query(self, text: str) -> List[float]:
"""Embed a text.
Args:
text: The text to embed.
Returns:
Embedding for the text.
"""
embeddings = self.embed([text], 1, "RETRIEVAL_QUERY")
return embeddings[0]
