perf: optimize memory allocation on building object path (#18465)

Signed-off-by: MrCroxx <[email protected]>

src/storage/hummock_sdk/src/lib.rs

@@ -130,6 +130,7 @@ pub const FIRST_VERSION_ID: HummockVersionId = HummockVersionId(1);
 pub const SPLIT_TABLE_COMPACTION_GROUP_ID_HEAD: u64 = 1u64 << 56;
 pub const SINGLE_TABLE_COMPACTION_GROUP_ID_HEAD: u64 = 2u64 << 56;
 pub const OBJECT_SUFFIX: &str = "data";
+pub const HUMMOCK_SSTABLE_OBJECT_ID_MAX_DECIMAL_LENGTH: usize = 20;
 
 #[macro_export]
 /// This is wrapper for `info` log.
@@ -359,3 +360,14 @@ impl EpochWithGap {
         self.0 & EPOCH_SPILL_TIME_MASK
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_object_id_decimal_max_length() {
+        let len = HummockSstableObjectId::MAX.to_string().len();
+        assert_eq!(len, HUMMOCK_SSTABLE_OBJECT_ID_MAX_DECIMAL_LENGTH)
+    }
+}

src/storage/src/hummock/sstable_store.rs

@@ -26,7 +26,9 @@ use foyer::{
 use futures::{future, StreamExt};
 use itertools::Itertools;
 use risingwave_hummock_sdk::sstable_info::SstableInfo;
-use risingwave_hummock_sdk::{HummockSstableObjectId, OBJECT_SUFFIX};
+use risingwave_hummock_sdk::{
+    HummockSstableObjectId, HUMMOCK_SSTABLE_OBJECT_ID_MAX_DECIMAL_LENGTH, OBJECT_SUFFIX,
+};
 use risingwave_hummock_trace::TracedCachePolicy;
 use risingwave_object_store::object::{
     ObjectError, ObjectMetadataIter, ObjectResult, ObjectStoreRef, ObjectStreamingUploader,
@@ -519,10 +521,21 @@ impl SstableStore {
         let obj_prefix = self
             .store
             .get_object_prefix(object_id, self.use_new_object_prefix_strategy);
-        format!(
-            "{}/{}{}.{}",
-            self.path, obj_prefix, object_id, OBJECT_SUFFIX
-        )
+        let mut path = String::with_capacity(
+            self.path.len()
+                + "/".len()
+                + obj_prefix.len()
+                + HUMMOCK_SSTABLE_OBJECT_ID_MAX_DECIMAL_LENGTH
+                + ".".len()
+                + OBJECT_SUFFIX.len(),
+        );
+        path.push_str(&self.path);
+        path.push('/');
+        path.push_str(&obj_prefix);
+        path.push_str(&object_id.to_string());
+        path.push('.');
+        path.push_str(OBJECT_SUFFIX);
+        path
     }
 
     pub fn get_object_id_from_path(path: &str) -> HummockSstableObjectId {