Sampling: Add rudimentary DRY support

Adds DRY support based on the current exl2 dev API. Only change for
optimization is dry_max_ngram instead of using a closed range.

Currently, DRY range is aliased to dry_max_ngram.

Signed-off-by: kingbri <bdashore3@proton.me>

backends/exllamav2/model.py

@@ -7,6 +7,7 @@ import pathlib
 import traceback
 import torch
 import uuid
+from copy import deepcopy
 from exllamav2 import (
     ExLlamaV2,
     ExLlamaV2Config,
@@ -944,6 +945,14 @@ class ExllamaV2Container:
         Meant for dev wheels!
         """
 
+        if unwrap(kwargs.get("dry_allowed_length"), 0) > 0 and not hasattr(
+            ExLlamaV2Sampler.Settings, "dry_multiplier"
+        ):
+            logger.warning(
+                "DRY sampling is not supported by the currently "
+                "installed ExLlamaV2 version."
+            )
+
         return kwargs
 
     async def generate_gen(
@@ -1035,6 +1044,7 @@ class ExllamaV2Container:
                     "Please use an ampere (30 series) or higher GPU for CFG support."
                 )
 
+        # Penalties
         gen_settings.token_repetition_penalty = unwrap(
             kwargs.get("repetition_penalty"), 1.0
         )
@@ -1070,6 +1080,23 @@ class ExllamaV2Container:
             kwargs.get("repetition_decay"), fallback_decay, 0
         )
 
+        # DRY options
+        dry_allowed_length = unwrap(kwargs.get("dry_allowed_length"), 0)
+
+        # 0 = disabled
+        if dry_allowed_length:
+            gen_settings.dry_allowed_length = dry_allowed_length
+            gen_settings.dry_base = unwrap(kwargs.get("dry_base"), 2.0)
+            gen_settings.dry_multiplier = unwrap(kwargs.get("dry_multiplier"), 2.0)
+            gen_settings.dry_max_ngram = unwrap(kwargs.get("dry_max_ngram"), 20)
+
+            # Tokenize sequence breakers
+            dry_sequence_breakers_json = kwargs.get("dry_sequence_breakers")
+            if dry_sequence_breakers_json:
+                gen_settings.dry_sequence_breakers = {
+                    self.encode_tokens(s)[-1] for s in dry_sequence_breakers_json
+                }
+
         # Initialize grammar handler
         grammar_handler = ExLlamaV2Grammar()
 
@@ -1130,7 +1157,8 @@ class ExllamaV2Container:
             )
 
         # Store the gen settings for logging purposes
-        gen_settings_log_dict = vars(gen_settings)
+        # Deepcopy to save a snapshot of vars
+        gen_settings_log_dict = deepcopy(vars(gen_settings))
 
         # Set banned tokens
         banned_tokens = unwrap(kwargs.get("banned_tokens"), [])