122 lines
4.2 KiB
Rust
122 lines
4.2 KiB
Rust
use async_trait::async_trait;
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use rand::Rng;
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use rand_pcg::Pcg64;
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use rand_seeder::Seeder;
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use std::fmt;
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use minisql::operation::ColumnSelection;
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use minisql::restricted_row::RestrictedRow;
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use minisql::schema::{Column, TableSchema};
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use proto::message::backend::{BackendMessage, ColumnDescription, CommandCompleteData, DataRowData, ErrorResponseData, ReadyForQueryData, RowDescriptionData};
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use proto::message::primitive::pglist::PgList;
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use proto::writer::backend::BackendProtoWriter;
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pub enum CompleteStatus {
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Insert {
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oid: i32,
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rows: i32,
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},
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Delete(usize),
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Select(usize),
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CreateTable,
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CreateIndex,
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}
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impl fmt::Display for CompleteStatus {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match self {
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CompleteStatus::Insert { oid, rows } => write!(f, "INSERT {} {}", oid, rows),
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CompleteStatus::Delete(rows) => write!(f, "DELETE {}", rows),
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CompleteStatus::Select(rows) => write!(f, "SELECT {}", rows),
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CompleteStatus::CreateTable => write!(f, "CREATE TABLE"),
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CompleteStatus::CreateIndex => write!(f, "CREATE INDEX"),
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}
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}
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}
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#[async_trait]
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pub trait ServerProto {
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async fn write_error_message(&mut self, error_message: &str) -> anyhow::Result<()>;
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async fn write_ready_for_query(&mut self) -> anyhow::Result<()>;
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async fn write_empty_query(&mut self) -> anyhow::Result<()>;
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async fn write_table_header(&mut self, table_schema: &TableSchema, columns: &ColumnSelection) -> anyhow::Result<()>;
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async fn write_table_row(&mut self, row: &RestrictedRow) -> anyhow::Result<()>;
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async fn write_command_complete(&mut self, status: CompleteStatus) -> anyhow::Result<()>;
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}
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#[async_trait]
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impl<W> ServerProto for W where W: BackendProtoWriter + Send {
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async fn write_error_message(&mut self, error_message: &str) -> anyhow::Result<()> {
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self.write_proto(ErrorResponseData {
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code: b'M',
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message: format!("{error_message}\0").into(),
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}.into()).await?;
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Ok(())
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}
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async fn write_ready_for_query(&mut self) -> anyhow::Result<()> {
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self.write_proto(ReadyForQueryData { status: b'I' }.into()).await?;
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Ok(())
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}
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async fn write_empty_query(&mut self) -> anyhow::Result<()> {
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self.write_proto(BackendMessage::EmptyQueryResponse).await?;
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Ok(())
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}
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async fn write_table_header(&mut self, table_schema: &TableSchema, columns: &ColumnSelection) -> anyhow::Result<()> {
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let columns = columns.iter()
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.map(|column| column_to_description(table_schema, *column))
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.collect::<anyhow::Result<Vec<ColumnDescription>>>()?;
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self.write_proto(RowDescriptionData { columns: columns.into() }.into()).await?;
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Ok(())
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}
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async fn write_table_row(&mut self, row: &RestrictedRow) -> anyhow::Result<()> {
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let values = row.iter()
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.map(|(_, value)| value.as_text_bytes().into())
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.collect::<Vec<PgList<u8, i32>>>();
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self.write_proto(BackendMessage::DataRow(DataRowData {
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columns: values.into(),
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})).await?;
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Ok(())
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}
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async fn write_command_complete(&mut self, status: CompleteStatus) -> anyhow::Result<()> {
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self.write_proto(BackendMessage::CommandComplete(CommandCompleteData {
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tag: status.to_string().into(),
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})).await?;
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Ok(())
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}
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}
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fn column_to_description(schema: &TableSchema, column: Column) -> anyhow::Result<ColumnDescription> {
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let table_name = schema.table_name();
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let table_oid = table_name_to_oid(table_name);
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let column_type = schema.column_type(column);
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let name = schema.column_name_from_column(column);
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let column_index = column.try_into()?;
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let type_oid = column_type.type_oid();
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let type_size = column_type.type_size();
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Ok(ColumnDescription {
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name: name.to_string().into(),
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table_oid,
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column_index,
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type_oid,
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type_size,
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type_modifier: -1,
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format_code: 0, // text format
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})
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}
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/// Hashes the table name into single i32 used as a substitute for the table OID
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/// in the PostgreSQL protocol.
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fn table_name_to_oid(table_name: &str) -> i32 {
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let mut rng: Pcg64 = Seeder::from(table_name).make_rng();
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rng.gen::<i32>()
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}
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