From 8e1977685713c68ff483fe02e010deaa685b453a Mon Sep 17 00:00:00 2001
From: Dan Goodliffe <dan@randomdan.homeip.net>
Date: Thu, 22 Jul 2021 23:09:36 +0100
Subject: First cut replicating row updates

---
 lib/output/pq/updateDatabase.cpp | 59 +++++++++++++++++++++++++++++++++++++++-
 lib/output/pq/updateDatabase.h   | 16 ++++++++++-
 2 files changed, 73 insertions(+), 2 deletions(-)

(limited to 'lib')

diff --git a/lib/output/pq/updateDatabase.cpp b/lib/output/pq/updateDatabase.cpp
index 6a0f419..9659cc0 100644
--- a/lib/output/pq/updateDatabase.cpp
+++ b/lib/output/pq/updateDatabase.cpp
@@ -19,6 +19,7 @@
 #include <output/pq/sql/selectSource.h>
 #include <output/pq/sql/selectSourceSchema.h>
 #include <output/pq/sql/selectTables.h>
+#include <row.h>
 #include <stdexcept>
 #include <streamSupport.h>
 
@@ -33,7 +34,8 @@ namespace MyGrate::Output::Pq {
 	}
 
 	UpdateDatabase::UpdateDatabase(PqConn && conn, uint64_t s, RecordSetPtr cfg) :
-		PqConn {std::move(conn)}, source {s}, schema(cfg->at(0, 0)), database(cfg->at(0, 1))
+		PqConn {std::move(conn)}, source {s}, schema(cfg->at(0, 0)),
+		database(cfg->at(0, 1)), selected {tables.end()}, table_map {nullptr, nullptr}
 	{
 		auto trecs = output::pq::sql::selectTables::execute(this, source);
 		auto crecs = output::pq::sql::selectColumns::execute(this, source);
@@ -227,4 +229,59 @@ namespace MyGrate::Output::Pq {
 
 		fclose(out);
 	}
+
+	void
+	UpdateDatabase::tableMap(MariaDB_Event_Ptr e)
+	{
+		if (*e->event.table_map.database == database) {
+			selected = tables.find(*e->event.table_map.table);
+			table_map = std::move(e);
+		}
+		else {
+			selected = tables.end();
+			table_map.reset();
+		}
+	}
+
+	void
+	UpdateDatabase::updateRow(MariaDB_Event_Ptr e)
+	{
+		if (selected != tables.end()) {
+			auto & out = selected->second;
+			verify<std::runtime_error>(
+					e->event.rows.column_count == out->columns.size(), "Incorrect number of columns in row data");
+			if (!out->update) {
+				std::stringstream ou;
+				std::size_t ordinal {0}, kordinal {out->columns.size()};
+
+				scprintf<"UPDATE %?.%? ">(ou, schema, selected->first);
+				for (const auto & col : out->columns) {
+					scprintf<"%? %? = $%?">(ou, !ordinal ? " SET " : ", ", col->name, ordinal + 1);
+					ordinal++;
+				}
+				for (const auto & col : out->columns) {
+					if (col->is_pk) {
+						scprintf<"%? %? = $%?">(
+								ou, kordinal == out->columns.size() ? " WHERE " : " AND ", col->name, kordinal + 1);
+						kordinal++;
+					}
+				}
+
+				out->update = prepare(ou.str().c_str(), kordinal);
+			}
+			std::vector<DbValue> updateValues;
+			updateValues.reserve(
+					out->columns.size() + std::count_if(out->columns.begin(), out->columns.end(), [](auto && c) {
+						return c->is_pk;
+					}));
+			RowPair rp {e->event.rows, table_map->event.table_map};
+			std::copy(rp.second.begin(), rp.second.end(), std::back_inserter(updateValues));
+			std::copy_if(rp.first.begin(), rp.first.end(), std::back_inserter(updateValues),
+					[c = out->columns.begin()](auto &&) mutable {
+						return (c++)->get()->is_pk;
+					});
+			out->update->execute(updateValues);
+			verify<ReplicationError>(out->update->rows() == 1, "Wrong number of rows updated.");
+		}
+	}
 }
diff --git a/lib/output/pq/updateDatabase.h b/lib/output/pq/updateDatabase.h
index 79df9a9..aa50e90 100644
--- a/lib/output/pq/updateDatabase.h
+++ b/lib/output/pq/updateDatabase.h
@@ -2,6 +2,7 @@
 #define MYGRATE_OUTPUT_PQ_UPDATEDATABASE_H
 
 #include "pqConn.h"
+#include "pqStmt.h"
 #include <cstdint>
 #include <eventHandlerBase.h>
 #include <eventSourceBase.h>
@@ -25,6 +26,7 @@ namespace MyGrate::Output::Pq {
 		TableOutput(const RecordSet &, std::string_view name);
 
 		std::vector<ColumnDefPtr> columns;
+		DbPrepStmtPtr update;
 	};
 	using TableDefPtr = std::unique_ptr<TableOutput>;
 
@@ -32,6 +34,10 @@ namespace MyGrate::Output::Pq {
 		using std::runtime_error::runtime_error;
 	};
 
+	class ReplicationError : public std::runtime_error {
+		using std::runtime_error::runtime_error;
+	};
+
 	class UpdateDatabase : public PqConn, public EventHandlerBase {
 	public:
 		UpdateDatabase(const char * const str, uint64_t source);
@@ -44,6 +50,10 @@ namespace MyGrate::Output::Pq {
 		void addTable(Input::MySQLConn *, const char * tableName);
 		void copyTableContent(Input::MySQLConn *, const char * tableName);
 
+		// Replication events
+		void updateRow(MariaDB_Event_Ptr) override;
+		void tableMap(MariaDB_Event_Ptr) override;
+
 		const uint64_t source;
 		const std::string schema;
 		const std::string database;
@@ -51,7 +61,11 @@ namespace MyGrate::Output::Pq {
 	private:
 		UpdateDatabase(PqConn &&, uint64_t source);
 		UpdateDatabase(PqConn &&, uint64_t source, RecordSetPtr cfg);
-		std::map<std::string, TableDefPtr, std::less<>> tables;
+
+		using Tables = std::map<std::string, TableDefPtr, std::less<>>;
+		Tables tables;
+		Tables::const_iterator selected;
+		MariaDB_Event_Ptr table_map;
 	};
 }
 
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