forked from projectmoon/tenebrous-dicebot
Custom schema violation error for DB value retrieval.
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parent
4234263ee4
commit
4856360c6a
15
src/db.rs
15
src/db.rs
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@ -4,6 +4,11 @@ use thiserror::Error;
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use zerocopy::byteorder::I32;
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use zerocopy::{AsBytes, LayoutVerified};
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/// User variables are stored as little-endian 32-bit integers in the
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/// database. This type alias makes the database code more pleasant to
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/// read.
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type LittleEndianI32Layout<'a> = LayoutVerified<&'a [u8], I32<LittleEndian>>;
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#[derive(Clone)]
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pub struct Database {
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db: Db,
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@ -14,6 +19,9 @@ pub enum DataError {
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#[error("value does not exist for key: {0}")]
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KeyDoesNotExist(String),
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#[error("key violates expected schema: {0}")]
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SchemaViolation(String),
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#[error("internal database error: {0}")]
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InternalError(#[from] sled::Error),
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}
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@ -40,11 +48,14 @@ impl Database {
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let key = to_key(room_id, username, variable_name);
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if let Some(raw_value) = self.db.get(&key)? {
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let layout: LayoutVerified<&[u8], I32<LittleEndian>> =
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LayoutVerified::new_unaligned(&*raw_value).expect("bytes do not fit schema");
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let layout = LittleEndianI32Layout::new_unaligned(raw_value.as_ref());
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if let Some(layout) = layout {
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let value: I32<LittleEndian> = *layout;
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Ok(value.get())
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} else {
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Err(DataError::SchemaViolation(String::from_utf8(key).unwrap()))
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}
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} else {
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Err(DataError::KeyDoesNotExist(String::from_utf8(key).unwrap()))
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}
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