@@ -11,6 +11,7 @@ package http
1111
1212import (
1313 "bufio"
14+ "compress/flate"
1415 "compress/gzip"
1516 "container/list"
1617 "context"
@@ -2988,6 +2989,7 @@ type bodyEOFSignal struct {
29882989}
29892990
29902991var errReadOnClosedResBody = errors .New ("http: read on closed response body" )
2992+ var errConcurrentReadOnResBody = errors .New ("http: concurrent read on response body" )
29912993
29922994func (es * bodyEOFSignal ) Read (p []byte ) (n int , err error ) {
29932995 es .mu .Lock ()
@@ -3037,37 +3039,98 @@ func (es *bodyEOFSignal) condfn(err error) error {
30373039}
30383040
30393041// gzipReader wraps a response body so it can lazily
3040- // call gzip.NewReader on the first call to Read
3042+ // get gzip.Reader from the pool on the first call to Read.
3043+ // After Close is called it puts gzip.Reader to the pool immediately
3044+ // if there is no Read in progress or later when Read completes.
30413045type gzipReader struct {
30423046 _ incomparable
30433047 body * bodyEOFSignal // underlying HTTP/1 response body framing
3044- zr * gzip.Reader // lazily-initialized gzip reader
3045- zerr error // any error from gzip.NewReader; sticky
3048+ mu sync.Mutex // guards zr and zerr
3049+ zr * gzip.Reader
3050+ zerr error
30463051}
30473052
3048- func (gz * gzipReader ) Read (p []byte ) (n int , err error ) {
3053+ type eofReader struct {}
3054+ 3055+ func (eofReader ) Read ([]byte ) (int , error ) { return 0 , io .EOF }
3056+ func (eofReader ) ReadByte () (byte , error ) { return 0 , io .EOF }
3057+ 3058+ var gzipPool = sync.Pool {New : func () any { return new (gzip.Reader ) }}
3059+ 3060+ // gzipPoolGet gets a gzip.Reader from the pool and resets it to read from r.
3061+ func gzipPoolGet (r io.Reader ) (* gzip.Reader , error ) {
3062+ zr := gzipPool .Get ().(* gzip.Reader )
3063+ if err := zr .Reset (r ); err != nil {
3064+ gzipPoolPut (zr )
3065+ return nil , err
3066+ }
3067+ return zr , nil
3068+ }
3069+ 3070+ // gzipPoolPut puts a gzip.Reader back into the pool.
3071+ func gzipPoolPut (zr * gzip.Reader ) {
3072+ // Reset will allocate bufio.Reader if we pass it anything
3073+ // other than a flate.Reader, so ensure that it's getting one.
3074+ var r flate.Reader = eofReader {}
3075+ zr .Reset (r )
3076+ gzipPool .Put (zr )
3077+ }
3078+ 3079+ // acquire returns a gzip.Reader for reading response body.
3080+ // The reader must be released after use.
3081+ func (gz * gzipReader ) acquire () (* gzip.Reader , error ) {
3082+ gz .mu .Lock ()
3083+ defer gz .mu .Unlock ()
3084+ if gz .zerr != nil {
3085+ return nil , gz .zerr
3086+ }
30493087 if gz .zr == nil {
3050- if gz .zerr == nil {
3051- gz .zr , gz .zerr = gzip .NewReader (gz .body )
3052- }
3088+ gz .zr , gz .zerr = gzipPoolGet (gz .body )
30533089 if gz .zerr != nil {
3054- return 0 , gz .zerr
3090+ return nil , gz .zerr
30553091 }
30563092 }
3093+ ret := gz .zr
3094+ gz .zr , gz .zerr = nil , errConcurrentReadOnResBody
3095+ return ret , nil
3096+ }
3097+ 3098+ // release returns the gzip.Reader to the pool if Close was called during Read.
3099+ func (gz * gzipReader ) release (zr * gzip.Reader ) {
3100+ gz .mu .Lock ()
3101+ defer gz .mu .Unlock ()
3102+ if gz .zerr == errConcurrentReadOnResBody {
3103+ gz .zr , gz .zerr = zr , nil
3104+ } else { // errReadOnClosedResBody
3105+ gzipPoolPut (zr )
3106+ }
3107+ }
30573108
3058- gz .body .mu .Lock ()
3059- if gz .body .closed {
3060- err = errReadOnClosedResBody
3109+ // close returns the gzip.Reader to the pool immediately or
3110+ // signals release to do so after Read completes.
3111+ func (gz * gzipReader ) close () {
3112+ gz .mu .Lock ()
3113+ defer gz .mu .Unlock ()
3114+ if gz .zerr == nil && gz .zr != nil {
3115+ gzipPoolPut (gz .zr )
3116+ gz .zr = nil
30613117 }
3062- gz .body .mu .Unlock ()
3118+ gz .zerr = errReadOnClosedResBody
3119+ }
30633120
3121+ func (gz * gzipReader ) Read (p []byte ) (n int , err error ) {
3122+ zr , err := gz .acquire ()
30643123 if err != nil {
30653124 return 0 , err
30663125 }
3067- return gz .zr .Read (p )
3126+ defer gz .release (zr )
3127+ 3128+ return zr .Read (p )
30683129}
30693130
30703131func (gz * gzipReader ) Close () error {
3132+ gz .close ()
3133+ 30713134 return gz .body .Close ()
30723135}
30733136
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