File size: 6,090 Bytes
d90101d | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 | use aws_sdk_bedrockruntime::operation::converse_stream::ConverseStreamInput;
use aws_sdk_bedrockruntime::types::{
CachePointBlock, CachePointType, ContentBlock, SystemContentBlock,
};
use forge_domain::Transformer;
/// Transformer that implements a simple two-breakpoint cache strategy for
/// Bedrock:
/// - Always caches after the first system message
/// - Always caches after the last message in the conversation
///
/// This follows AWS Bedrock's caching model where CachePoint blocks are
/// inserted at strategic positions to enable prompt caching.
pub struct SetCache;
// TODO: Implement it on Context or Conversation instead of ConverseStreamInput
impl Transformer for SetCache {
type Value = ConverseStreamInput;
/// Implements a simple two-breakpoint cache strategy:
/// 1. Cache after the first system message (if exists)
/// 2. Cache after the last message
fn transform(&mut self, mut request: Self::Value) -> Self::Value {
let sys_len = request.system.as_ref().map_or(0, |msgs| msgs.len());
let msg_len = request.messages.as_ref().map_or(0, |msgs| msgs.len());
if sys_len == 0 && msg_len == 0 {
return request;
}
// Add cache point after first system message
if let Some(system_messages) = request.system.as_mut()
&& !system_messages.is_empty()
{
system_messages.insert(
1,
SystemContentBlock::CachePoint(
CachePointBlock::builder()
.r#type(CachePointType::Default)
.build()
.expect("Failed to build CachePointBlock"),
),
);
}
// Add cache point at the end of the last message's content
if let Some(messages) = request.messages.as_mut()
&& let Some(last_message) = messages.last_mut()
{
last_message.content.push(ContentBlock::CachePoint(
CachePointBlock::builder()
.r#type(CachePointType::Default)
.build()
.expect("Failed to build CachePointBlock"),
));
}
request
}
}
#[cfg(test)]
mod tests {
use forge_domain::{Context, ContextMessage, Role, TextMessage};
use pretty_assertions::assert_eq;
use super::*;
use crate::provider::FromDomain;
fn has_cache_point_after_first_system(request: &ConverseStreamInput) -> bool {
request
.system
.as_ref()
.and_then(|sys| sys.get(1))
.map(|block| matches!(block, SystemContentBlock::CachePoint(_)))
.unwrap_or(false)
}
fn has_cache_point_in_last_message(request: &ConverseStreamInput) -> bool {
request
.messages
.as_ref()
.and_then(|msgs| msgs.last())
.map(|msg| {
msg.content
.iter()
.any(|block| matches!(block, ContentBlock::CachePoint(_)))
})
.unwrap_or(false)
}
#[test]
fn test_single_user_message() {
let context = Context {
conversation_id: None,
messages: vec![ContextMessage::Text(TextMessage::new(Role::User, "Hello")).into()],
tools: vec![],
tool_choice: None,
max_tokens: None,
temperature: None,
top_p: None,
top_k: None,
reasoning: None,
stream: None,
response_format: None,
initiator: None,
};
let request = ConverseStreamInput::from_domain(context).expect("Failed to convert context");
let mut transformer = SetCache;
let actual = transformer.transform(request);
assert_eq!(has_cache_point_after_first_system(&actual), false);
assert_eq!(has_cache_point_in_last_message(&actual), true);
}
#[test]
fn test_with_system_message() {
let context = Context {
conversation_id: None,
messages: vec![
ContextMessage::Text(TextMessage::new(Role::System, "System prompt")).into(),
ContextMessage::Text(TextMessage::new(Role::User, "Hello")).into(),
],
tools: vec![],
tool_choice: None,
max_tokens: None,
temperature: None,
top_p: None,
top_k: None,
reasoning: None,
stream: None,
response_format: None,
initiator: None,
};
let request = ConverseStreamInput::from_domain(context).expect("Failed to convert context");
let mut transformer = SetCache;
let actual = transformer.transform(request);
assert_eq!(has_cache_point_after_first_system(&actual), true);
assert_eq!(has_cache_point_in_last_message(&actual), true);
}
#[test]
fn test_multiple_messages() {
let context = Context {
conversation_id: None,
messages: vec![
ContextMessage::Text(TextMessage::new(Role::System, "System prompt")).into(),
ContextMessage::Text(TextMessage::new(Role::User, "Hello")).into(),
ContextMessage::Text(TextMessage::new(Role::Assistant, "Hi there")).into(),
ContextMessage::Text(TextMessage::new(Role::User, "How are you?")).into(),
],
tools: vec![],
tool_choice: None,
max_tokens: None,
temperature: None,
top_p: None,
top_k: None,
reasoning: None,
stream: None,
response_format: None,
initiator: None,
};
let request = ConverseStreamInput::from_domain(context).expect("Failed to convert context");
let mut transformer = SetCache;
let actual = transformer.transform(request);
assert_eq!(has_cache_point_after_first_system(&actual), true);
assert_eq!(has_cache_point_in_last_message(&actual), true);
}
}
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