Move get_target_and_anchor_heights to data_api.

zcash_client_backend/src/data_api/chain.rs

@@ -1,4 +1,6 @@
-use zcash_primitives::consensus::{self, NetworkUpgrade};
+use std::cmp;
+
+use zcash_primitives::consensus::{self, BlockHeight, NetworkUpgrade};
 
 use crate::data_api::{
     error::{ChainInvalid, Error},
@@ -77,3 +79,27 @@ pub fn validate_combined_chain<
         }
     }
 }
+
+/// Determines the target height for a transaction, and the height from which to
+/// select anchors, based on the current synchronised block chain.
+pub fn get_target_and_anchor_heights<E, D: DBOps<Error = Error<E>>>(
+    data: &D,
+) -> Result<(BlockHeight, BlockHeight), Error<E>> {
+    data.block_height_extrema().and_then(|heights| {
+        match heights {
+            Some((min_height, max_height)) => {
+                let target_height = max_height + 1;
+
+                // Select an anchor ANCHOR_OFFSET back from the target block,
+                // unless that would be before the earliest block we have.
+                let anchor_height = BlockHeight::from(cmp::max(
+                    u32::from(target_height).saturating_sub(ANCHOR_OFFSET),
+                    u32::from(min_height),
+                ));
+
+                Ok((target_height, anchor_height))
+            }
+            None => Err(Error::ScanRequired),
+        }
+    })
+}

zcash_client_sqlite/src/lib.rs

@@ -24,8 +24,7 @@
 //! [`CompactBlock`]: zcash_client_backend::proto::compact_formats::CompactBlock
 //! [`init_cache_database`]: crate::init::init_cache_database
 
-use rusqlite::{Connection, NO_PARAMS};
-use std::cmp;
+use rusqlite::Connection;
 use std::path::Path;
 
 use zcash_primitives::{
@@ -35,13 +34,11 @@ use zcash_primitives::{
 };
 
 use zcash_client_backend::{
-    data_api::{chain::ANCHOR_OFFSET, error::Error, CacheOps, DBOps},
+    data_api::{error::Error, CacheOps, DBOps},
     encoding::encode_payment_address,
     proto::compact_formats::CompactBlock,
 };
 
-use crate::error::SqliteClientError;
-
 pub mod chain;
 pub mod error;
 pub mod init;
@@ -110,38 +107,6 @@ fn address_from_extfvk<P: consensus::Parameters>(
     encode_payment_address(params.hrp_sapling_payment_address(), &addr)
 }
 
-/// Determines the target height for a transaction, and the height from which to
-/// select anchors, based on the current synchronised block chain.
-fn get_target_and_anchor_heights(
-    data: &DataConnection,
-) -> Result<(BlockHeight, BlockHeight), SqliteClientError> {
-    data.0.query_row_and_then(
-        "SELECT MIN(height), MAX(height) FROM blocks",
-        NO_PARAMS,
-        |row| match (row.get::<_, u32>(0), row.get::<_, u32>(1)) {
-            // If there are no blocks, the query returns NULL.
-            (Err(rusqlite::Error::InvalidColumnType(_, _, _)), _)
-            | (_, Err(rusqlite::Error::InvalidColumnType(_, _, _))) => {
-                Err(Error::ScanRequired.into())
-            }
-            (Err(e), _) | (_, Err(e)) => Err(e.into()),
-            (Ok(min_height), Ok(max_height)) => {
-                let target_height = max_height + 1;
-
-                // Select an anchor ANCHOR_OFFSET back from the target block,
-                // unless that would be before the earliest block we have.
-                let anchor_height =
-                    cmp::max(target_height.saturating_sub(ANCHOR_OFFSET), min_height);
-
-                Ok((
-                    BlockHeight::from(target_height),
-                    BlockHeight::from(anchor_height),
-                ))
-            }
-        },
-    )
-}
-
 #[cfg(test)]
 mod tests {
     use ff::PrimeField;

zcash_client_sqlite/src/query.rs

@@ -2,9 +2,9 @@
 
 use zcash_primitives::{note_encryption::Memo, transaction::components::Amount};
 
-use zcash_client_backend::data_api::error::Error;
+use zcash_client_backend::data_api::{chain::get_target_and_anchor_heights, error::Error};
 
-use crate::{error::SqliteClientError, get_target_and_anchor_heights, DataConnection};
+use crate::{error::SqliteClientError, DataConnection};
 
 /// Returns the address for the account.
 ///
@@ -90,7 +90,7 @@ pub fn get_verified_balance(
     data: &DataConnection,
     account: u32,
 ) -> Result<Amount, SqliteClientError> {
-    let (_, anchor_height) = get_target_and_anchor_heights(&data)?;
+    let (_, anchor_height) = get_target_and_anchor_heights(data)?;
 
     let balance = data.0.query_row(
         "SELECT SUM(value) FROM received_notes

zcash_client_sqlite/src/transact.rs

@@ -3,9 +3,7 @@
 use ff::PrimeField;
 use rusqlite::{types::ToSql, NO_PARAMS};
 use std::convert::TryInto;
-use zcash_client_backend::{
-    address::RecipientAddress, data_api::error::Error, encoding::encode_extended_full_viewing_key,
-};
+
 use zcash_primitives::{
     consensus,
     keys::OutgoingViewingKey,
@@ -21,7 +19,13 @@ use zcash_primitives::{
     zip32::{ExtendedFullViewingKey, ExtendedSpendingKey},
 };
 
-use crate::{error::SqliteClientError, get_target_and_anchor_heights, DataConnection};
+use zcash_client_backend::{
+    address::RecipientAddress,
+    data_api::{chain::get_target_and_anchor_heights, error::Error},
+    encoding::encode_extended_full_viewing_key,
+};
+
+use crate::{error::SqliteClientError, DataConnection};
 
 /// Describes a policy for which outgoing viewing key should be able to decrypt
 /// transaction outputs.
@@ -164,7 +168,7 @@ pub fn create_to_address<P: consensus::Parameters>(
     };
 
     // Target the next block, assuming we are up-to-date.
-    let (height, anchor_height) = get_target_and_anchor_heights(&data)?;
+    let (height, anchor_height) = get_target_and_anchor_heights(data)?;
 
     // The goal of this SQL statement is to select the oldest notes until the required
     // value has been reached, and then fetch the witnesses at the desired height for the