Upgrading bert example to work with bert-base-uncased.

- Always take weights from the hub
- Optional `model_id` + `revision` to use safetensors version
  potentially
- Optional loading for `bert-base-uncased` (`weight` vs `gamma`).
- Take the config from the hub.

candle-examples/examples/bert/main.rs

@@ -1,10 +1,9 @@
 #![allow(dead_code)]
-// The tokenizer.json and weights should be retrieved from:
-// https://huggingface.co/sentence-transformers/all-MiniLM-L6-v2
-
 use anyhow::{Error as E, Result};
 use candle::{safetensors::SafeTensors, DType, Device, Shape, Tensor};
+use candle_hub::{api::Api, Repo, RepoType};
 use clap::Parser;
+use serde::Deserialize;
 use std::collections::HashMap;
 
 const DTYPE: DType = DType::F32;
@@ -66,7 +65,8 @@ impl<'a> VarBuilder<'a> {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "lowercase")]
 enum HiddenAct {
     Gelu,
     Relu,
@@ -84,13 +84,14 @@ impl HiddenAct {
     }
 }
 
-#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Deserialize)]
+#[serde(rename_all = "lowercase")]
 enum PositionEmbeddingType {
     Absolute,
 }
 
 // https://github.com/huggingface/transformers/blob/6eedfa6dd15dc1e22a55ae036f681914e5a0d9a1/src/transformers/models/bert/configuration_bert.py#L1
-#[derive(Debug, Clone, PartialEq)]
+#[derive(Debug, Clone, PartialEq, Deserialize)]
 struct Config {
     vocab_size: usize,
     hidden_size: usize,
@@ -235,8 +236,22 @@ impl LayerNorm {
     }
 
     fn load(size: usize, eps: f64, p: &str, vb: &VarBuilder) -> Result<Self> {
-        let weight = vb.get(size, &format!("{p}.weight"))?;
-        let bias = vb.get(size, &format!("{p}.bias"))?;
+        let (weight, bias) = match (
+            vb.get(size, &format!("{p}.weight")),
+            vb.get(size, &format!("{p}.bias")),
+        ) {
+            (Ok(weight), Ok(bias)) => (weight, bias),
+            (Err(err), _) | (_, Err(err)) => {
+                if let (Ok(weight), Ok(bias)) = (
+                    vb.get(size, &format!("{p}.gamma")),
+                    vb.get(size, &format!("{p}.beta")),
+                ) {
+                    (weight, bias)
+                } else {
+                    return Err(err.into());
+                }
+            }
+        };
         Ok(Self { weight, bias, eps })
     }
 
@@ -567,8 +582,21 @@ struct BertModel {
 
 impl BertModel {
     fn load(vb: &VarBuilder, config: &Config) -> Result<Self> {
-        let embeddings = BertEmbeddings::load("embeddings", vb, config)?;
-        let encoder = BertEncoder::load("encoder", vb, config)?;
+        let (embeddings, encoder) = match (
+            BertEmbeddings::load("embeddings", vb, config),
+            BertEncoder::load("encoder", vb, config),
+        ) {
+            (Ok(embeddings), Ok(encoder)) => (embeddings, encoder),
+            (Err(err), _) | (_, Err(err)) => {
+                match (
+                    BertEmbeddings::load("bert.embeddings", vb, config),
+                    BertEncoder::load("bert.encoder", vb, config),
+                ) {
+                    (Ok(embeddings), Ok(encoder)) => (embeddings, encoder),
+                    _ => return Err(err),
+                }
+            }
+        };
         Ok(Self {
             embeddings,
             encoder,
@@ -590,13 +618,14 @@ struct Args {
     cpu: bool,
 
     #[arg(long)]
-    tokenizer_config: String,
+    model_id: Option<String>,
 
     #[arg(long)]
-    weights: String,
+    revision: Option<String>,
 }
 
-fn main() -> Result<()> {
+#[tokio::main]
+async fn main() -> Result<()> {
     use tokenizers::Tokenizer;
 
     let args = Args::parse();
@@ -606,13 +635,29 @@ fn main() -> Result<()> {
         Device::new_cuda(0)?
     };
 
-    let mut tokenizer = Tokenizer::from_file(args.tokenizer_config).map_err(E::msg)?;
+    let default_model = "sentence-transformers/all-MiniLM-L6-v2".to_string();
+    let default_revision = "refs/pr/21".to_string();
+    let (model_id, revision) = match (args.model_id, args.revision) {
+        (Some(model_id), Some(revision)) => (model_id, revision),
+        (Some(model_id), None) => (model_id, "main".to_string()),
+        (None, Some(revision)) => (default_model, revision),
+        (None, None) => (default_model, default_revision),
+    };
+
+    let api = Api::new()?;
+    let repo = Repo::with_revision(model_id, RepoType::Model, revision);
+    println!("building the model");
+    let config_filename = api.get(&repo, "config.json").await?;
+    let config = std::fs::read_to_string(config_filename)?;
+    let config: Config = serde_json::from_str(&config)?;
+    let tokenizer_filename = api.get(&repo, "tokenizer.json").await?;
+    let mut tokenizer = Tokenizer::from_file(tokenizer_filename).map_err(E::msg)?;
     let tokenizer = tokenizer.with_padding(None).with_truncation(None);
 
-    let weights = unsafe { candle::safetensors::MmapedFile::new(args.weights)? };
+    let weights = api.get(&repo, "model.safetensors").await?;
+    let weights = unsafe { candle::safetensors::MmapedFile::new(weights)? };
     let weights = weights.deserialize()?;
     let vb = VarBuilder::from_safetensors(vec![weights], DTYPE, device.clone());
-    let config = Config::all_mini_lm_l6_v2();
     let model = BertModel::load(&vb, &config)?;
 
     let tokens = tokenizer