gitroast/vendor/github.com/mattn/go-sqlite3/tracecallback.go

416 lines
12 KiB
Go

// Copyright (C) 2016 Yasuhiro Matsumoto <mattn.jp@gmail.com>.
// TODO: add "Gimpl do foo" team?
//
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
// +build trace
package sqlite3
/*
#ifndef USE_LIBSQLITE3
#include <sqlite3-binding.h>
#else
#include <sqlite3.h>
#endif
#include <stdlib.h>
void stepTrampoline(sqlite3_context*, int, sqlite3_value**);
void doneTrampoline(sqlite3_context*);
void traceCallbackTrampoline(unsigned traceEventCode, void *ctx, void *p, void *x);
*/
import "C"
import (
"errors"
"fmt"
"reflect"
"strings"
"sync"
"unsafe"
)
// Trace... constants identify the possible events causing callback invocation.
// Values are same as the corresponding SQLite Trace Event Codes.
const (
TraceStmt = C.SQLITE_TRACE_STMT
TraceProfile = C.SQLITE_TRACE_PROFILE
TraceRow = C.SQLITE_TRACE_ROW
TraceClose = 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 uint
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 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) int {
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 traceEventCode == 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, traceEventCode))
}
var info TraceInfo
info.EventCode = uint32(traceEventCode)
info.AutoCommit = (int(C.sqlite3_get_autocommit(contextDB)) != 0)
info.ConnHandle = connHandle
switch traceEventCode {
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&traceEventCode == 0 {
return 0
}
r := 0
if traceConf.Callback != nil {
r = traceConf.Callback(info)
}
return 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
}
// RegisterAggregator makes a Go type available as a SQLite aggregation function.
//
// Because aggregation is incremental, it's implemented in Go with a
// type that has 2 methods: func Step(values) accumulates one row of
// data into the accumulator, and func Done() ret finalizes and
// returns the aggregate value. "values" and "ret" may be any type
// supported by RegisterFunc.
//
// RegisterAggregator takes as implementation a constructor function
// that constructs an instance of the aggregator type each time an
// aggregation begins. The constructor must return a pointer to a
// type, or an interface that implements Step() and Done().
//
// The constructor function and the Step/Done methods may optionally
// return an error in addition to their other return values.
//
// See _example/go_custom_funcs for a detailed example.
func (c *SQLiteConn) RegisterAggregator(name string, impl interface{}, pure bool) error {
var ai aggInfo
ai.constructor = reflect.ValueOf(impl)
t := ai.constructor.Type()
if t.Kind() != reflect.Func {
return errors.New("non-function passed to RegisterAggregator")
}
if t.NumOut() != 1 && t.NumOut() != 2 {
return errors.New("SQLite aggregator constructors must return 1 or 2 values")
}
if t.NumOut() == 2 && !t.Out(1).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
return errors.New("Second return value of SQLite function must be error")
}
if t.NumIn() != 0 {
return errors.New("SQLite aggregator constructors must not have arguments")
}
agg := t.Out(0)
switch agg.Kind() {
case reflect.Ptr, reflect.Interface:
default:
return errors.New("SQlite aggregator constructor must return a pointer object")
}
stepFn, found := agg.MethodByName("Step")
if !found {
return errors.New("SQlite aggregator doesn't have a Step() function")
}
step := stepFn.Type
if step.NumOut() != 0 && step.NumOut() != 1 {
return errors.New("SQlite aggregator Step() function must return 0 or 1 values")
}
if step.NumOut() == 1 && !step.Out(0).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
return errors.New("type of SQlite aggregator Step() return value must be error")
}
stepNArgs := step.NumIn()
start := 0
if agg.Kind() == reflect.Ptr {
// Skip over the method receiver
stepNArgs--
start++
}
if step.IsVariadic() {
stepNArgs--
}
for i := start; i < start+stepNArgs; i++ {
conv, err := callbackArg(step.In(i))
if err != nil {
return err
}
ai.stepArgConverters = append(ai.stepArgConverters, conv)
}
if step.IsVariadic() {
conv, err := callbackArg(t.In(start + stepNArgs).Elem())
if err != nil {
return err
}
ai.stepVariadicConverter = conv
// Pass -1 to sqlite so that it allows any number of
// arguments. The call helper verifies that the minimum number
// of arguments is present for variadic functions.
stepNArgs = -1
}
doneFn, found := agg.MethodByName("Done")
if !found {
return errors.New("SQlite aggregator doesn't have a Done() function")
}
done := doneFn.Type
doneNArgs := done.NumIn()
if agg.Kind() == reflect.Ptr {
// Skip over the method receiver
doneNArgs--
}
if doneNArgs != 0 {
return errors.New("SQlite aggregator Done() function must have no arguments")
}
if done.NumOut() != 1 && done.NumOut() != 2 {
return errors.New("SQLite aggregator Done() function must return 1 or 2 values")
}
if done.NumOut() == 2 && !done.Out(1).Implements(reflect.TypeOf((*error)(nil)).Elem()) {
return errors.New("second return value of SQLite aggregator Done() function must be error")
}
conv, err := callbackRet(done.Out(0))
if err != nil {
return err
}
ai.doneRetConverter = conv
ai.active = make(map[int64]reflect.Value)
ai.next = 1
// ai must outlast the database connection, or we'll have dangling pointers.
c.aggregators = append(c.aggregators, &ai)
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
opts := C.SQLITE_UTF8
if pure {
opts |= C.SQLITE_DETERMINISTIC
}
rv := C._sqlite3_create_function(c.db, cname, C.int(stepNArgs), C.int(opts), C.uintptr_t(newHandle(c, &ai)), nil, (*[0]byte)(unsafe.Pointer(C.stepTrampoline)), (*[0]byte)(unsafe.Pointer(C.doneTrampoline)))
if rv != C.SQLITE_OK {
return c.lastError()
}
return nil
}
// 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 := 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
}