feat(rerankers): Add new backend, support jina rerankers API (#2121)

Signed-off-by: Ettore Di Giacinto <mudler@localai.io>

backend/python/rerankers/Makefile

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+.PHONY: rerankers
+rerankers: protogen
+	$(MAKE) -C ../common-env/transformers
+
+
+.PHONY: run
+run: protogen
+	@echo "Running rerankers..."
+	bash run.sh
+	@echo "rerankers run."
+
+# It is not working well by using command line. It only6 works with IDE like VSCode.
+.PHONY: test
+test: protogen
+	@echo "Testing rerankers..."
+	bash test.sh
+	@echo "rerankers tested."
+
+.PHONY: protogen
+protogen: backend_pb2_grpc.py backend_pb2.py
+
+.PHONY: protogen-clean
+protogen-clean:
+	$(RM) backend_pb2_grpc.py backend_pb2.py
+
+backend_pb2_grpc.py backend_pb2.py:
+	python3 -m grpc_tools.protoc -I../.. --python_out=. --grpc_python_out=. backend.proto

backend/python/rerankers/README.md

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+# Creating a separate environment for the reranker project
+
+```
+make reranker
+```

backend/python/rerankers/reranker.py

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+#!/usr/bin/env python3
+"""
+Extra gRPC server for Rerankers models.
+"""
+from concurrent import futures
+
+import argparse
+import signal
+import sys
+import os
+
+import time
+import backend_pb2
+import backend_pb2_grpc
+
+import grpc
+
+from rerankers import Reranker
+
+_ONE_DAY_IN_SECONDS = 60 * 60 * 24
+
+# If MAX_WORKERS are specified in the environment use it, otherwise default to 1
+MAX_WORKERS = int(os.environ.get('PYTHON_GRPC_MAX_WORKERS', '1'))
+
+# Implement the BackendServicer class with the service methods
+class BackendServicer(backend_pb2_grpc.BackendServicer):
+    """
+    A gRPC servicer for the backend service.
+
+    This class implements the gRPC methods for the backend service, including Health, LoadModel, and Embedding.
+    """
+    def Health(self, request, context):
+        """
+        A gRPC method that returns the health status of the backend service.
+
+        Args:
+            request: A HealthRequest object that contains the request parameters.
+            context: A grpc.ServicerContext object that provides information about the RPC.
+
+        Returns:
+            A Reply object that contains the health status of the backend service.
+        """
+        return backend_pb2.Reply(message=bytes("OK", 'utf-8'))
+
+    def LoadModel(self, request, context):
+        """
+        A gRPC method that loads a model into memory.
+
+        Args:
+            request: A LoadModelRequest object that contains the request parameters.
+            context: A grpc.ServicerContext object that provides information about the RPC.
+
+        Returns:
+            A Result object that contains the result of the LoadModel operation.
+        """
+        model_name = request.Model
+        try:
+            kwargs = {}
+            if request.Type != "":
+                kwargs['model_type'] = request.Type
+            if request.PipelineType != "": # Reuse the PipelineType field for language
+                kwargs['lang'] = request.PipelineType
+            self.model_name = model_name
+            self.model = Reranker(model_name, **kwargs)  
+        except Exception as err:
+            return backend_pb2.Result(success=False, message=f"Unexpected {err=}, {type(err)=}")
+
+        # Implement your logic here for the LoadModel service
+        # Replace this with your desired response
+        return backend_pb2.Result(message="Model loaded successfully", success=True)
+
+    def Rerank(self, request, context):
+        documents = []
+        for idx, doc in enumerate(request.documents):
+            documents.append(doc)
+        ranked_results=self.model.rank(query=request.query, docs=documents, doc_ids=list(range(len(request.documents))))
+        # Prepare results to return
+        results = [
+            backend_pb2.DocumentResult(
+                index=res.doc_id,
+                text=res.text,
+                relevance_score=res.score
+            ) for res in ranked_results.results
+        ]
+
+        # Calculate the usage and total tokens
+        # TODO: Implement the usage calculation with reranker
+        total_tokens = sum(len(doc.split()) for doc in request.documents) + len(request.query.split())
+        prompt_tokens = len(request.query.split())
+        usage = backend_pb2.Usage(total_tokens=total_tokens, prompt_tokens=prompt_tokens)
+        return backend_pb2.RerankResult(usage=usage, results=results)
+
+def serve(address):
+    server = grpc.server(futures.ThreadPoolExecutor(max_workers=MAX_WORKERS))
+    backend_pb2_grpc.add_BackendServicer_to_server(BackendServicer(), server)
+    server.add_insecure_port(address)
+    server.start()
+    print("Server started. Listening on: " + address, file=sys.stderr)
+
+    # Define the signal handler function
+    def signal_handler(sig, frame):
+        print("Received termination signal. Shutting down...")
+        server.stop(0)
+        sys.exit(0)
+
+    # Set the signal handlers for SIGINT and SIGTERM
+    signal.signal(signal.SIGINT, signal_handler)
+    signal.signal(signal.SIGTERM, signal_handler)
+
+    try:
+        while True:
+            time.sleep(_ONE_DAY_IN_SECONDS)
+    except KeyboardInterrupt:
+        server.stop(0)
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Run the gRPC server.")
+    parser.add_argument(
+        "--addr", default="localhost:50051", help="The address to bind the server to."
+    )
+    args = parser.parse_args()
+
+    serve(args.addr)

backend/python/rerankers/run.sh

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+#!/bin/bash
+
+##
+## A bash script wrapper that runs the reranker server with conda
+
+export PATH=$PATH:/opt/conda/bin
+
+# Activate conda environment
+source activate transformers
+
+# get the directory where the bash script is located
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+python $DIR/reranker.py $@

backend/python/rerankers/test.sh

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+#!/bin/bash
+##
+## A bash script wrapper that runs the reranker server with conda
+
+# Activate conda environment
+source activate transformers
+
+# get the directory where the bash script is located
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+
+python -m unittest $DIR/test_reranker.py

backend/python/rerankers/test_reranker.py

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+"""
+A test script to test the gRPC service
+"""
+import unittest
+import subprocess
+import time
+import backend_pb2
+import backend_pb2_grpc
+
+import grpc
+
+
+class TestBackendServicer(unittest.TestCase):
+    """
+    TestBackendServicer is the class that tests the gRPC service
+    """
+    def setUp(self):
+        """
+        This method sets up the gRPC service by starting the server
+        """
+        self.service = subprocess.Popen(["python3", "reranker.py", "--addr", "localhost:50051"])
+        time.sleep(10)
+
+    def tearDown(self) -> None:
+        """
+        This method tears down the gRPC service by terminating the server
+        """
+        self.service.kill()
+        self.service.wait()
+
+    def test_server_startup(self):
+        """
+        This method tests if the server starts up successfully
+        """
+        try:
+            self.setUp()
+            with grpc.insecure_channel("localhost:50051") as channel:
+                stub = backend_pb2_grpc.BackendStub(channel)
+                response = stub.Health(backend_pb2.HealthMessage())
+                self.assertEqual(response.message, b'OK')
+        except Exception as err:
+            print(err)
+            self.fail("Server failed to start")
+        finally:
+            self.tearDown()
+
+    def test_load_model(self):
+        """
+        This method tests if the model is loaded successfully
+        """
+        try:
+            self.setUp()
+            with grpc.insecure_channel("localhost:50051") as channel:
+                stub = backend_pb2_grpc.BackendStub(channel)
+                response = stub.LoadModel(backend_pb2.ModelOptions(Model="cross-encoder"))
+                self.assertTrue(response.success)
+                self.assertEqual(response.message, "Model loaded successfully")
+        except Exception as err:
+            print(err)
+            self.fail("LoadModel service failed")
+        finally:
+            self.tearDown()
+
+    def test_rerank(self):
+        """
+        This method tests if the embeddings are generated successfully
+        """
+        try:
+            self.setUp()
+            with grpc.insecure_channel("localhost:50051") as channel:
+                stub = backend_pb2_grpc.BackendStub(channel)
+                request = backend_pb2.RerankRequest(
+                    query="I love you",
+                    documents=["I hate you", "I really like you"],
+                    top_n=2
+                )
+                response = stub.LoadModel(backend_pb2.ModelOptions(Model="cross-encoder"))
+                self.assertTrue(response.success)
+               
+                rerank_response = stub.Rerank(request)
+                print(rerank_response.results[0])
+                self.assertIsNotNone(rerank_response.results)
+                self.assertEqual(len(rerank_response.results), 2)
+                self.assertEqual(rerank_response.results[0].text, "I really like you")
+                self.assertEqual(rerank_response.results[1].text, "I hate you")
+        except Exception as err:
+            print(err)
+            self.fail("Reranker service failed")
+        finally:
+            self.tearDown()