From e1dd117e7a0d4bcc7a18b5fb8b61cea4298a78a5 Mon Sep 17 00:00:00 2001 From: s441433 Date: Fri, 28 Dec 2018 22:13:25 +0100 Subject: [PATCH] Create sqlite3_trace.go --- .../mattn/go-sqlite3/sqlite3_trace.go | 288 ++++++++++++++++++ 1 file changed, 288 insertions(+) create mode 100644 src/github.com/mattn/go-sqlite3/sqlite3_trace.go diff --git a/src/github.com/mattn/go-sqlite3/sqlite3_trace.go b/src/github.com/mattn/go-sqlite3/sqlite3_trace.go new file mode 100644 index 0000000..ee93a0f --- /dev/null +++ b/src/github.com/mattn/go-sqlite3/sqlite3_trace.go @@ -0,0 +1,288 @@ +// Copyright (C) 2016 Yasuhiro Matsumoto . +// +// Use of this source code is governed by an MIT-style +// license that can be found in the LICENSE file. + +// +build sqlite_trace trace + +package sqlite3 + +/* +#ifndef USE_LIBSQLITE3 +#include +#else +#include +#endif +#include + +int traceCallbackTrampoline(unsigned int traceEventCode, void *ctx, void *p, void *x); +*/ +import "C" + +import ( + "fmt" + "strings" + "sync" + "unsafe" +) + +// Trace... constants identify the possible events causing callback invocation. +// Values are same as the corresponding SQLite Trace Event Codes. +const ( + TraceStmt = uint32(C.SQLITE_TRACE_STMT) + TraceProfile = uint32(C.SQLITE_TRACE_PROFILE) + TraceRow = uint32(C.SQLITE_TRACE_ROW) + TraceClose = uint32(C.SQLITE_TRACE_CLOSE) +) + +type TraceInfo struct { + // Pack together the shorter fields, to keep the struct smaller. + // On a 64-bit machine there would be padding + // between EventCode and ConnHandle; having AutoCommit here is "free": + EventCode uint32 + AutoCommit bool + ConnHandle uintptr + + // Usually filled, unless EventCode = TraceClose = SQLITE_TRACE_CLOSE: + // identifier for a prepared statement: + StmtHandle uintptr + + // Two strings filled when EventCode = TraceStmt = SQLITE_TRACE_STMT: + // (1) either the unexpanded SQL text of the prepared statement, or + // an SQL comment that indicates the invocation of a trigger; + // (2) expanded SQL, if requested and if (1) is not an SQL comment. + StmtOrTrigger string + ExpandedSQL string // only if requested (TraceConfig.WantExpandedSQL = true) + + // filled when EventCode = TraceProfile = SQLITE_TRACE_PROFILE: + // estimated number of nanoseconds that the prepared statement took to run: + RunTimeNanosec int64 + + DBError Error +} + +// TraceUserCallback gives the signature for a trace function +// provided by the user (Go application programmer). +// SQLite 3.14 documentation (as of September 2, 2016) +// for SQL Trace Hook = sqlite3_trace_v2(): +// The integer return value from the callback is currently ignored, +// though this may change in future releases. Callback implementations +// should return zero to ensure future compatibility. +type TraceUserCallback func(TraceInfo) int + +type TraceConfig struct { + Callback TraceUserCallback + EventMask uint32 + WantExpandedSQL bool +} + +func fillDBError(dbErr *Error, db *C.sqlite3) { + // See SQLiteConn.lastError(), in file 'sqlite3.go' at the time of writing (Sept 5, 2016) + dbErr.Code = ErrNo(C.sqlite3_errcode(db)) + dbErr.ExtendedCode = ErrNoExtended(C.sqlite3_extended_errcode(db)) + dbErr.err = C.GoString(C.sqlite3_errmsg(db)) +} + +func fillExpandedSQL(info *TraceInfo, db *C.sqlite3, pStmt unsafe.Pointer) { + if pStmt == nil { + panic("No SQLite statement pointer in P arg of trace_v2 callback") + } + + expSQLiteCStr := C.sqlite3_expanded_sql((*C.sqlite3_stmt)(pStmt)) + if expSQLiteCStr == nil { + fillDBError(&info.DBError, db) + return + } + info.ExpandedSQL = C.GoString(expSQLiteCStr) +} + +//export traceCallbackTrampoline +func traceCallbackTrampoline( + traceEventCode C.uint, + // Parameter named 'C' in SQLite docs = Context given at registration: + ctx unsafe.Pointer, + // Parameter named 'P' in SQLite docs (Primary event data?): + p unsafe.Pointer, + // Parameter named 'X' in SQLite docs (eXtra event data?): + xValue unsafe.Pointer) C.int { + + eventCode := uint32(traceEventCode) + + if ctx == nil { + panic(fmt.Sprintf("No context (ev 0x%x)", traceEventCode)) + } + + contextDB := (*C.sqlite3)(ctx) + connHandle := uintptr(ctx) + + var traceConf TraceConfig + var found bool + if eventCode == TraceClose { + // clean up traceMap: 'pop' means get and delete + traceConf, found = popTraceMapping(connHandle) + } else { + traceConf, found = lookupTraceMapping(connHandle) + } + + if !found { + panic(fmt.Sprintf("Mapping not found for handle 0x%x (ev 0x%x)", + connHandle, eventCode)) + } + + var info TraceInfo + + info.EventCode = eventCode + info.AutoCommit = (int(C.sqlite3_get_autocommit(contextDB)) != 0) + info.ConnHandle = connHandle + + switch eventCode { + case TraceStmt: + info.StmtHandle = uintptr(p) + + var xStr string + if xValue != nil { + xStr = C.GoString((*C.char)(xValue)) + } + info.StmtOrTrigger = xStr + if !strings.HasPrefix(xStr, "--") { + // Not SQL comment, therefore the current event + // is not related to a trigger. + // The user might want to receive the expanded SQL; + // let's check: + if traceConf.WantExpandedSQL { + fillExpandedSQL(&info, contextDB, p) + } + } + + case TraceProfile: + info.StmtHandle = uintptr(p) + + if xValue == nil { + panic("NULL pointer in X arg of trace_v2 callback for SQLITE_TRACE_PROFILE event") + } + + info.RunTimeNanosec = *(*int64)(xValue) + + // sample the error //TODO: is it safe? is it useful? + fillDBError(&info.DBError, contextDB) + + case TraceRow: + info.StmtHandle = uintptr(p) + + case TraceClose: + handle := uintptr(p) + if handle != info.ConnHandle { + panic(fmt.Sprintf("Different conn handle 0x%x (expected 0x%x) in SQLITE_TRACE_CLOSE event.", + handle, info.ConnHandle)) + } + + default: + // Pass unsupported events to the user callback (if configured); + // let the user callback decide whether to panic or ignore them. + } + + // Do not execute user callback when the event was not requested by user! + // Remember that the Close event is always selected when + // registering this callback trampoline with SQLite --- for cleanup. + // In the future there may be more events forced to "selected" in SQLite + // for the driver's needs. + if traceConf.EventMask&eventCode == 0 { + return 0 + } + + r := 0 + if traceConf.Callback != nil { + r = traceConf.Callback(info) + } + return C.int(r) +} + +type traceMapEntry struct { + config TraceConfig +} + +var traceMapLock sync.Mutex +var traceMap = make(map[uintptr]traceMapEntry) + +func addTraceMapping(connHandle uintptr, traceConf TraceConfig) { + traceMapLock.Lock() + defer traceMapLock.Unlock() + + oldEntryCopy, found := traceMap[connHandle] + if found { + panic(fmt.Sprintf("Adding trace config %v: handle 0x%x already registered (%v).", + traceConf, connHandle, oldEntryCopy.config)) + } + traceMap[connHandle] = traceMapEntry{config: traceConf} + fmt.Printf("Added trace config %v: handle 0x%x.\n", traceConf, connHandle) +} + +func lookupTraceMapping(connHandle uintptr) (TraceConfig, bool) { + traceMapLock.Lock() + defer traceMapLock.Unlock() + + entryCopy, found := traceMap[connHandle] + return entryCopy.config, found +} + +// 'pop' = get and delete from map before returning the value to the caller +func popTraceMapping(connHandle uintptr) (TraceConfig, bool) { + traceMapLock.Lock() + defer traceMapLock.Unlock() + + entryCopy, found := traceMap[connHandle] + if found { + delete(traceMap, connHandle) + fmt.Printf("Pop handle 0x%x: deleted trace config %v.\n", connHandle, entryCopy.config) + } + return entryCopy.config, found +} + +// SetTrace installs or removes the trace callback for the given database connection. +// It's not named 'RegisterTrace' because only one callback can be kept and called. +// Calling SetTrace a second time on same database connection +// overrides (cancels) any prior callback and all its settings: +// event mask, etc. +func (c *SQLiteConn) SetTrace(requested *TraceConfig) error { + connHandle := uintptr(unsafe.Pointer(c.db)) + + _, _ = popTraceMapping(connHandle) + + if requested == nil { + // The traceMap entry was deleted already by popTraceMapping(): + // can disable all events now, no need to watch for TraceClose. + err := c.setSQLiteTrace(0) + return err + } + + reqCopy := *requested + + // Disable potentially expensive operations + // if their result will not be used. We are doing this + // just in case the caller provided nonsensical input. + if reqCopy.EventMask&TraceStmt == 0 { + reqCopy.WantExpandedSQL = false + } + + addTraceMapping(connHandle, reqCopy) + + // The callback trampoline function does cleanup on Close event, + // regardless of the presence or absence of the user callback. + // Therefore it needs the Close event to be selected: + actualEventMask := uint(reqCopy.EventMask | TraceClose) + err := c.setSQLiteTrace(actualEventMask) + return err +} + +func (c *SQLiteConn) setSQLiteTrace(sqliteEventMask uint) error { + rv := C.sqlite3_trace_v2(c.db, + C.uint(sqliteEventMask), + (*[0]byte)(unsafe.Pointer(C.traceCallbackTrampoline)), + unsafe.Pointer(c.db)) // Fourth arg is same as first: we are + // passing the database connection handle as callback context. + + if rv != C.SQLITE_OK { + return c.lastError() + } + return nil +}