feat: Deduplicate tagged blobs #5512
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crusso
reviewed
Sep 26, 2025
luc-blaeser
reviewed
Oct 6, 2025
rts/motoko-rts/src/persistence.rs
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| /// Setter method for the dedup table. | ||
| pub(crate) unsafe fn set_dedup_table_ptr(dedup_table: Value) { | ||
| let metadata = PersistentMetadata::get(); | ||
| (*metadata).dedup_table = dedup_table; |
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I believe here a write barrier would be needed.
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fixed, thank you!
luc-blaeser
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Oct 6, 2025
alexandru-uta
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luc-blaeser
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Oct 14, 2025
This PR adds (tagged) blob deduplication support. The main issue it solves is that all external calls to a motoko canister go through candid deserialization and blobs passed as arguments end up as fresh blobs on the motoko heap. Calling multiple times with the same blob as argument creates multiple copies of the same blob. To achieve deduplication, this PR does the following: * in `internals.mo`, it creates a fixed-size hash-table which solves collisions via chaining. * sets up a thin RTS interface to set/get the hash-table allocated in `internals.mo` to be tracked by the RTS layer such that the table is not garbage collected and it survives upgrades. * to achieve deduplication, the hash table stores weak references pointing to the actual objects; once objects are garbage collected, the weak references will point to null. * a thin client interface (in `prim.mo`) to walk the hash table and check which deduplicated blobs are alive/dead and prune the dead ones if neeed.
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This PR adds (tagged) blob deduplication support. The main issue it solves is that all external calls to a motoko canister go through candid deserialization and blobs passed as arguments end up as fresh blobs on the motoko heap. Calling multiple times with the same blob as argument creates multiple copies of the same blob.
To achieve deduplication, this PR does the following:
internals.mo, it creates a fixed-size hash-table which solves collisions via chaining.internals.moto be tracked by the RTS layer such that the table is not garbage collected and it survives upgrades.prim.mo) to walk the hash table and check which deduplicated blobs are alive/dead and prune the dead ones if neeed.