@@ -11,6 +11,7 @@ package http
1111
1212import (
1313 "bufio"
14+ "compress/flate"
1415 "compress/gzip"
1516 "container/list"
1617 "context"
@@ -2976,6 +2977,7 @@ type bodyEOFSignal struct {
29762977}
29772978
29782979var errReadOnClosedResBody = errors .New ("http: read on closed response body" )
2980+ var errConcurrentReadOnResBody = errors .New ("http: concurrent read on response body" )
29792981
29802982func (es * bodyEOFSignal ) Read (p []byte ) (n int , err error ) {
29812983 es .mu .Lock ()
@@ -3025,37 +3027,98 @@ func (es *bodyEOFSignal) condfn(err error) error {
30253027}
30263028
30273029// gzipReader wraps a response body so it can lazily
3028- // call gzip.NewReader on the first call to Read
3030+ // get gzip.Reader from the pool on the first call to Read.
3031+ // After Close is called it puts gzip.Reader to the pool immediately
3032+ // if there is no Read in progress or later when Read completes.
30293033type gzipReader struct {
30303034 _ incomparable
30313035 body * bodyEOFSignal // underlying HTTP/1 response body framing
3032- zr * gzip.Reader // lazily-initialized gzip reader
3033- zerr error // any error from gzip.NewReader; sticky
3036+ mu sync.Mutex // guards zr and zerr
3037+ zr * gzip.Reader
3038+ zerr error
30343039}
30353040
3036- func (gz * gzipReader ) Read (p []byte ) (n int , err error ) {
3041+ type eofReader struct {}
3042+ 3043+ func (eofReader ) Read ([]byte ) (int , error ) { return 0 , io .EOF }
3044+ func (eofReader ) ReadByte () (byte , error ) { return 0 , io .EOF }
3045+ 3046+ var gzipPool = sync.Pool {New : func () any { return new (gzip.Reader ) }}
3047+ 3048+ // gzipPoolGet gets a gzip.Reader from the pool and resets it to read from r.
3049+ func gzipPoolGet (r io.Reader ) (* gzip.Reader , error ) {
3050+ zr := gzipPool .Get ().(* gzip.Reader )
3051+ if err := zr .Reset (r ); err != nil {
3052+ gzipPoolPut (zr )
3053+ return nil , err
3054+ }
3055+ return zr , nil
3056+ }
3057+ 3058+ // gzipPoolPut puts a gzip.Reader back into the pool.
3059+ func gzipPoolPut (zr * gzip.Reader ) {
3060+ // Reset will allocate bufio.Reader if we pass it anything
3061+ // other than a flate.Reader, so ensure that it's getting one.
3062+ var r flate.Reader = eofReader {}
3063+ zr .Reset (r )
3064+ gzipPool .Put (zr )
3065+ }
3066+ 3067+ // acquire returns a gzip.Reader for reading response body.
3068+ // The reader must be released after use.
3069+ func (gz * gzipReader ) acquire () (* gzip.Reader , error ) {
3070+ gz .mu .Lock ()
3071+ defer gz .mu .Unlock ()
3072+ if gz .zerr != nil {
3073+ return nil , gz .zerr
3074+ }
30373075 if gz .zr == nil {
3038- if gz .zerr == nil {
3039- gz .zr , gz .zerr = gzip .NewReader (gz .body )
3040- }
3076+ gz .zr , gz .zerr = gzipPoolGet (gz .body )
30413077 if gz .zerr != nil {
3042- return 0 , gz .zerr
3078+ return nil , gz .zerr
30433079 }
30443080 }
3081+ ret := gz .zr
3082+ gz .zr , gz .zerr = nil , errConcurrentReadOnResBody
3083+ return ret , nil
3084+ }
3085+ 3086+ // release returns the gzip.Reader to the pool if Close was called during Read.
3087+ func (gz * gzipReader ) release (zr * gzip.Reader ) {
3088+ gz .mu .Lock ()
3089+ defer gz .mu .Unlock ()
3090+ if gz .zerr == errConcurrentReadOnResBody {
3091+ gz .zr , gz .zerr = zr , nil
3092+ } else { // errReadOnClosedResBody
3093+ gzipPoolPut (zr )
3094+ }
3095+ }
30453096
3046- gz .body .mu .Lock ()
3047- if gz .body .closed {
3048- err = errReadOnClosedResBody
3097+ // close returns the gzip.Reader to the pool immediately or
3098+ // signals release to do so after Read completes.
3099+ func (gz * gzipReader ) close () {
3100+ gz .mu .Lock ()
3101+ defer gz .mu .Unlock ()
3102+ if gz .zerr == nil && gz .zr != nil {
3103+ gzipPoolPut (gz .zr )
3104+ gz .zr = nil
30493105 }
3050- gz .body .mu .Unlock ()
3106+ gz .zerr = errReadOnClosedResBody
3107+ }
30513108
3109+ func (gz * gzipReader ) Read (p []byte ) (n int , err error ) {
3110+ zr , err := gz .acquire ()
30523111 if err != nil {
30533112 return 0 , err
30543113 }
3055- return gz .zr .Read (p )
3114+ defer gz .release (zr )
3115+ 3116+ return zr .Read (p )
30563117}
30573118
30583119func (gz * gzipReader ) Close () error {
3120+ gz .close ()
3121+ 30593122 return gz .body .Close ()
30603123}
30613124
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