added implementation of DRY sampler

common/sampling.cpp

@@ -267,13 +267,18 @@ static llama_token_data_array llama_sampling_prepare_impl(
 
     const int n_vocab = llama_n_vocab(llama_get_model(ctx_main));
 
+    // repetition penalties
     const int32_t penalty_last_n  = params.penalty_last_n < 0 ? params.n_prev : params.penalty_last_n;
     const float   penalty_repeat  = params.penalty_repeat;
     const float   penalty_freq    = params.penalty_freq;
     const float   penalty_present = params.penalty_present;
-
     const bool    penalize_nl     = params.penalize_nl;
 
+    // DRY sampler parameters
+    const float   dry_multiplier        = params.dry_multiplier;
+    const float   dry_base              = params.dry_base;
+    const int     dry_allowed_length    = params.dry_allowed_length;
+
     auto & prev = ctx_sampling->prev;
     auto & cur  = ctx_sampling->cur;
 
@@ -309,10 +314,19 @@ static llama_token_data_array llama_sampling_prepare_impl(
     if (penalty_tokens_used_size) {
         const float nl_logit = logits[llama_token_nl(llama_get_model(ctx_main))];
 
+        // repetition penalties
         llama_sample_repetition_penalties(ctx_main, &cur_p,
                 penalty_tokens.data() + penalty_tokens.size() - penalty_tokens_used_size,
                 penalty_tokens_used_size, penalty_repeat, penalty_freq, penalty_present);
 
+        // DRY penalties (multiplier > 0 means enabled)
+        if(dry_multiplier > 0.0f) {
+            llama_sample_dry(ctx_main, &cur_p,
+                            penalty_tokens.data() + penalty_tokens.size() - penalty_tokens_used_size,
+                            penalty_tokens_used_size, dry_base, dry_multiplier, dry_allowed_length,
+                            params.dry_sequence_breakers.data(), params.dry_sequence_breakers.size());
+        }
+
         if (!penalize_nl) {
             for (size_t idx = 0; idx < cur_p.size; idx++) {
                 if (cur_p.data[idx].id == llama_token_nl(llama_get_model(ctx_main))) {

common/sampling.h

@@ -41,6 +41,9 @@ typedef struct llama_sampling_params {
     float       mirostat_eta          = 0.10f;              // learning rate
     bool        penalize_nl           = false;              // consider newlines as a repeatable token
     uint32_t    seed                  = LLAMA_DEFAULT_SEED; // the seed used to initialize llama_sampling_context
+    float       dry_multiplier        = 0.0f;     // 0.0f = disabled, recommended value: 0.8f
+    float       dry_base              = 1.75f;
+    int         dry_allowed_length    = 2;
 
     std::vector<llama_sampler_type> samplers_sequence = {
         llama_sampler_type::TOP_K,
@@ -61,6 +64,7 @@ typedef struct llama_sampling_params {
     std::unordered_map<llama_token, float> logit_bias; // logit bias for specific tokens
 
     std::vector<llama_token> penalty_prompt_tokens;
+    std::vector<llama_token> dry_sequence_breakers; // sequence breakers for the DRY sampler
     bool                     use_penalty_prompt_tokens = false;
 } llama_sampling_params;
 

llama.cpp

@@ -13233,6 +13233,90 @@ void llama_sample_min_p(struct llama_context * ctx, llama_token_data_array * can
     }
 }
 
+void llama_sample_dry(struct llama_context * ctx, llama_token_data_array * candidates, const llama_token * last_tokens, int last_tokens_size, float dry_base, float dry_multiplier, int dry_allowed_length, const llama_token * seq_breakers, int seq_breakers_size) {
+    // sanity check
+    GGML_ASSERT(last_tokens_size > 0);
+
+    // get the last token
+    auto last_token = last_tokens[last_tokens_size - 1];
+
+    // if last token is part of the sequence breakers, skip whole sampler
+    if(std::find(seq_breakers, seq_breakers + seq_breakers_size, last_token) != seq_breakers + seq_breakers_size) {
+        return;
+    }
+
+    // create an unordered map of "next tokens" <-> max match length
+    std::unordered_map<llama_token, size_t> match_lengths;
+
+    // loop through each previous token (exclude the last token)
+    for (size_t i = 0; i < last_tokens_size - 1; ++i) {
+        // skip if the compare token if it's not the same as the last token
+        if(last_tokens[i] != last_token) {
+            continue;
+        }
+
+        // get the next token (i + 1 is always less than last_tokens_size)
+        auto next_token = last_tokens[i + 1];
+
+        // try to extend the match backwards (match length starts a 1 because last token is already matched)
+        size_t match_length = 1;
+
+        // loop through the previous tokens
+        for(;; match_length++) {
+            // if we have reached the start of our last tokens, break
+            if(i < match_length) break;
+
+            // compare token starts at our prev index, going backwards by match length
+            auto compare_token = last_tokens[i - match_length];
+
+            // head token starts at the end of last tokens, going backwards by match length, minus 1 because we start at the last token itself
+            auto head_token = last_tokens[last_tokens_size - 1 - match_length];
+
+            // if compare token is part of the sequence breakers, break out of the match
+            if(std::find(seq_breakers, seq_breakers + seq_breakers_size, compare_token) != seq_breakers + seq_breakers_size)
+                break;
+
+            // break out of the match if any tokens don't match
+            if(compare_token != head_token)
+                break;
+        }
+
+        // Check if the next token exists in the map
+        auto it = match_lengths.find(next_token);
+
+        if (it == match_lengths.end()) {
+            // Key does not exist, insert the new value
+            match_lengths[next_token] = match_length;
+        } else {
+            // Key exists, update it with the max of the new value or the existing value
+            it->second = std::max(it->second, match_length);
+        }
+    }
+
+    // apply penalties
+    for (const auto& pair : match_lengths) {
+        auto next_token = pair.first;
+        auto match_length = pair.second;
+
+        // if the match length is greater than our allowed length in config, we apply penalities
+        if(match_length > dry_allowed_length) {
+
+            // find our next token in the candidates->data
+            size_t i = 0;
+            for (; i < candidates->size; ++i) {
+                if (candidates->data[i].id == next_token) {
+                    // calculate the penalty
+                    float penalty = dry_multiplier * pow(dry_base, match_length - dry_allowed_length);
+
+                    // apply the dry penalty
+                    candidates->data[i].logit -= penalty;
+                    break;
+                }
+            }
+        }
+    }
+}
+
 void llama_sample_tail_free(struct llama_context * ctx, llama_token_data_array * candidates, float z, size_t min_keep) {
     if (z >= 1.0f || candidates->size <= 2) {
         return;

llama.h

@@ -924,6 +924,18 @@ extern "C" {
                            float   p,
                           size_t   min_keep);
 
+    ///  @details DRY sampler as described in: https://github.com/oobabooga/text-generation-webui/pull/5677
+    LLAMA_API void llama_sample_dry(
+            struct llama_context * ctx,
+          llama_token_data_array * candidates,
+               const llama_token * last_tokens,
+                             int   last_tokens_size,
+                           float   dry_base,
+                           float   dry_multiplier,
+                             int   dry_allowed_length,
+               const llama_token * seq_breakers,
+                             int   seq_breakers_size);
+
     /// @details Tail Free Sampling described in https://www.trentonbricken.com/Tail-Free-Sampling/.
     LLAMA_API void llama_sample_tail_free(
             struct llama_context * ctx,