[taler-exchange] branch master updated: -wip

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grothoff pushed a commit to branch master
in repository exchange.

The following commit(s) were added to refs/heads/master by this push:
     new a7273486 -wip
a7273486 is described below

commit a7273486382c69b23356a110700665b18911d0db
Author: Christian Grothoff <christian@grothoff.org>
AuthorDate: Wed Dec 8 11:53:27 2021 +0100

    -wip
---
 src/exchangedb/melt.sql | 280 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 280 insertions(+)

diff --git a/src/exchangedb/melt.sql b/src/exchangedb/melt.sql
new file mode 100644
index 00000000..af1aa8d4
--- /dev/null
+++ b/src/exchangedb/melt.sql
@@ -0,0 +1,280 @@
+
+-- Everything in one big transaction
+-- BEGIN;
+
+-- Check patch versioning is in place.
+-- SELECT _v.register_patch('exchange-000x', NULL, NULL);
+
+CREATE OR REPLACE FUNCTION exchange_do_melt(
+  IN denom_val INT8, -- value of the denomination of the coin
+  IN denom_frac INT4, -- value of the denomination of the coin
+  IN amount_val INT8, -- requested melt amount (with fee)
+  IN amount_frac INT4, -- requested melt amount (with fee)
+  IN in_rc BYTEA, -- refresh session hash
+  IN in_coin_pub BYTEA, -- coin public key
+  IN coin_sig BYTEA, -- melt signature
+  IN in_noreveal_index INT4, -- suggested random noreveal index
+  IN zombie_required BOOLEAN, -- do we need a zombie coin?
+  OUT out_noreval_index INT4, -- noreveal index to actually use
+  OUT balance_ok BOOLEAN, -- balance satisfied?
+  OUT zombie_ok BOOLEAN, -- zombie satisfied?
+  OUT melt_ok BOOLEAN) -- everything OK?
+LANGUAGE plpgsql
+AS $$
+DECLARE
+  coin_uuid INT8; -- known_coin_id of coin_pub
+DECLARE
+  tmp_val INT8; -- temporary result
+DECLARE
+  tmp_frac INT8; -- temporary result
+DECLARE
+  spent_val INT8; -- how much of coin was spent?
+DECLARE
+  spent_frac INT8; -- how much of coin was spent?
+DECLARE
+  unspent_val INT8; -- how much of coin was refunded?
+DECLARE
+  unspent_frac INT8; -- how much of coin was refunded?
+BEGIN
+
+SELECT known_coin_id INTO coin_uuid
+  FROM known_coins
+ WHERE coin_pub=in_coin_pub;
+
+IF NOT FOUND
+THEN
+  -- coin unknown, should be impossible!
+  out_noreveal_index=-1;
+  balance_ok=FALSE;
+  zombie_ok=FALSE;
+  melt_ok=FALSE;
+  ASSERT false, 'coin unknown';
+  RETURN;
+END IF;
+
+-- We optimistically insert, and then on conflict declare
+-- the query successful due to idempotency.
+INSERT INTO refresh_commitments
+  (rc
+  ,old_known_coin_id
+  ,old_coin_sig
+  ,amount_with_fee_val
+  ,amount_with_fee_frac
+  ,noreveal_index)
+VALUES
+  (in_rc
+  ,coin_uuid
+  ,coin_sig
+  ,amount_val
+  ,amount_frac
+  ,in_noreveal_index)
+ON CONFLICT DO NOTHING;
+
+IF FOUND
+THEN
+  -- already melted, get noreveal_index
+  SELECT noreveal_index INTO out_noreveal_index
+    FROM refresh_commitments
+   WHERE rc=in_rc ;
+  balance_ok=TRUE;
+  zombie_ok=TRUE;
+  melt_ok=TRUE;
+  RETURN;
+END IF;
+
+-- Need to check for sufficient balance...
+spent_val = 0;
+spent_frac = 0;
+unspent_val = 0;
+unspent_frac = 0;
+
+SELECT
+   SUM(amount_with_fee_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_with_fee_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM deposits
+ WHERE known_coin_id=coin_uuid;
+
+spent_val = spent_val + tmp_val;
+spent_frac = spent_frac + tmp_frac;
+
+SELECT
+   SUM(amount_with_fee_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_with_fee_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM refresh_commitments
+ WHERE old_known_coin_id=coin_uuid;
+
+spent_val = spent_val + tmp_val;
+spent_frac = spent_frac + tmp_frac;
+
+SELECT
+   SUM(amount_with_fee_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_with_fee_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM refunds
+ WHERE known_coin_id=coin_uuid;
+
+unspent_val = unspent_val + tmp_val;
+unspent_frac = unspent_frac + tmp_frac;
+
+SELECT
+   SUM(amount_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM recoup_refresh
+ WHERE known_coin_id=coin_uuid;
+
+unspent_val = unspent_val + tmp_val;
+unspent_frac = unspent_frac + tmp_frac;
+
+SELECT
+   SUM(amount_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM recoup
+ WHERE known_coin_id=coin_uuid;
+
+spent_val = spent_val + tmp_val;
+spent_frac = spent_frac + tmp_frac;
+
+SELECT
+   SUM(amount_val) -- overflow here is not plausible
+  ,SUM(CAST(amount_frac AS INT8)) -- compute using 64 bits
+  INTO
+   tmp_val
+  ,tmp_frac
+  FROM recoup_refresh
+  JOIN refresh_revealed_coins rrc
+      USING (rrc_serial)
+  JOIN refresh_commitments rfc
+       ON (rrc.melt_serial_id = rfc.melt_serial_id)
+ WHERE rfc.old_known_coin_id=coin_uuid;
+
+spent_val = spent_val + tmp_val;
+spent_frac = spent_frac + tmp_frac;
+
+
+------------------- TBD from here
+
+SELECT
+   reserve_uuid
+  ,current_balance_val
+  ,current_balance_frac_uuid
+  ,expiration_date
+  ,gc_date
+ INTO
+   reserve_uuid
+  ,reserve_val
+  ,reserve_frac
+  ,reserve_gc
+  FROM reserves
+ WHERE reserve_pub=reserve_pub;
+
+IF NOT FOUND
+THEN
+  -- reserve unknown
+  reserve_found=FALSE;
+  balance_ok=FALSE;
+  kyc_ok=FALSE;
+  RETURN;
+END IF;
+
+-- We optimistically insert, and then on conflict declare
+-- the query successful due to idempotency.
+INSERT INTO reserves_out
+  (h_blind_ev
+  ,denom_serial
+  ,denom_sig
+  ,reserve_uuid
+  ,reserve_sig
+  ,execution_date
+  ,amount_with_fee_val
+  ,amount_with_fee_frac)
+VALUES
+  (h_coin_envelope
+  ,denom_serial
+  ,denom_sig
+  ,reserve_uuid
+  ,reserve_sig
+  ,now
+  ,amount_val
+  ,amount_frac)
+ON CONFLICT DO NOTHING;
+
+IF NOT FOUND
+THEN
+  -- idempotent query, all constraints must be satisfied
+  reserve_found=TRUE;
+  balance_ok=TRUE;
+  kyc_ok=TRUE;
+  RETURN;
+END IF;
+
+-- Check reserve balance is sufficient.
+IF (reserve_val > amount_val)
+THEN
+  IF (reserve_frac > amount_frac)
+  THEN
+    reserve_val=reserve_val - amount_val;
+    reserve_frac=reserve_frac - amount_frac;
+  ELSE
+    reserve_val=reserve_val - amount_val - 1;
+    reserve_frac=reserve_frac + 100000000 - amount_frac;
+  END IF;
+ELSE
+  IF (reserve_val == amount_val) AND (reserve_frac >= amount_frac)
+  THEN
+    reserve_val=0;
+    reserve_frac=reserve_frac - amount_frac;
+  ELSE
+    reserve_found=TRUE;
+    balance_ok=FALSE;
+    kyc_ok=FALSE; -- we do not really know or care
+    RETURN;
+  END IF;
+END IF;
+
+-- Calculate new expiration dates.
+min_reserve_gc=MAX(min_reserve_gc,reserve_gc);
+
+-- Update reserve balance.
+UPDATE reserves SET
+  gc_date=min_reserve_gc
+ ,current_balance_val=reserve_val
+ ,current_balance_frac=reserve_frac
+WHERE
+  reserve_uuid=reserve_uuid;
+
+reserve_found=TRUE;
+balance_ok=TRUE;
+
+-- Obtain KYC status based on the last wire transfer into
+-- this reserve. FIXME: likely not adequate for reserves that got P2P 
transfers!
+SELECT kyc_ok
+  INTO kyc_ok
+  FROM reserves_in
+  JOIN wire_targets USING (wire_target_serial_id)
+ WHERE reserve_uuid=reserve_uuid
+ LIMIT 1; -- limit 1 should not be required (without p2p transfers)
+
+
+
+END $$;
+
+COMMENT ON FUNCTION exchange_do_melt(INT8, INT4, BYTEA, BYTEA, BYTEA, BYTEA, 
BYTEA, INT8, INT8)
+  IS 'Checks whether the coin has sufficient balance for a melt operation (or 
the request is repeated and was previously approved) and if so updates the 
database with the result';
+
+
+-- Complete transaction
+-- COMMIT;

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