feat: use the context to thread sessions through all commands

* Ensure we have a single session per gateway request.
* Use a session in the ipfs refs command.
* Start a session before resolving the pin root (also fixes sessions while
  pinning).
* Update go-merkledag to reliably create sessions.

part of #7198

core/commands/pin.go

@@ -12,6 +12,7 @@ import (
 	cid "github.com/ipfs/go-cid"
 	cidenc "github.com/ipfs/go-cidutil/cidenc"
 	cmds "github.com/ipfs/go-ipfs-cmds"
+	exchange "github.com/ipfs/go-ipfs-exchange-interface"
 	offline "github.com/ipfs/go-ipfs-exchange-offline"
 	pin "github.com/ipfs/go-ipfs-pinner"
 	ipld "github.com/ipfs/go-ipld-format"
@@ -186,20 +187,32 @@ var addPinCmd = &cmds.Command{
 func pinAddMany(ctx context.Context, api coreiface.CoreAPI, enc cidenc.Encoder, paths []string, recursive bool) ([]string, error) {
 	added := make([]string, len(paths))
 	for i, b := range paths {
-		rp, err := api.ResolvePath(ctx, path.New(b))
+		rp, err := pinAdd(ctx, api, path.New(b), recursive)
 		if err != nil {
 			return nil, err
 		}
-
-		if err := api.Pin().Add(ctx, rp, options.Pin.Recursive(recursive)); err != nil {
-			return nil, err
-		}
 		added[i] = enc.Encode(rp.Cid())
 	}
 
 	return added, nil
 }
 
+func pinAdd(ctx context.Context, api coreiface.CoreAPI, path path.Path, recursive bool) (path.Resolved, error) {
+	ctx, cancel := context.WithCancel(ctx)
+	defer cancel()
+	ctx = exchange.NewSession(ctx)
+
+	rp, err := api.ResolvePath(ctx, path)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := api.Pin().Add(ctx, rp, options.Pin.Recursive(recursive)); err != nil {
+		return nil, err
+	}
+	return rp, nil
+}
+
 var rmPinCmd = &cmds.Command{
 	Helptext: cmds.HelpText{
 		Tagline: "Remove pinned objects from local storage.",

core/commands/refs.go

@@ -7,6 +7,7 @@ import (
 	"io"
 	"strings"
 
+	exchange "github.com/ipfs/go-ipfs-exchange-interface"
 	cmdenv "github.com/ipfs/go-ipfs/core/commands/cmdenv"
 
 	cid "github.com/ipfs/go-cid"
@@ -102,6 +103,12 @@ NOTE: List all references recursively by using the flag '-r'.
 			format = "<src> -> <dst>"
 		}
 
+		// Assume all these requests are related and put them into a
+		// single session.
+		ctx, cancel := context.WithCancel(ctx)
+		ctx = exchange.NewSession(ctx)
+		defer cancel()
+
 		objs, err := objectsForPaths(ctx, api, req.Arguments)
 		if err != nil {
 			return err

core/coreapi/pin.go

@@ -3,8 +3,10 @@ package coreapi
 import (
 	"context"
 	"fmt"
+
 	bserv "github.com/ipfs/go-blockservice"
 	"github.com/ipfs/go-cid"
+	exchange "github.com/ipfs/go-ipfs-exchange-interface"
 	offline "github.com/ipfs/go-ipfs-exchange-offline"
 	pin "github.com/ipfs/go-ipfs-pinner"
 	ipld "github.com/ipfs/go-ipld-format"
@@ -17,6 +19,8 @@ import (
 type PinAPI CoreAPI
 
 func (api *PinAPI) Add(ctx context.Context, p path.Path, opts ...caopts.PinAddOption) error {
+	ctx = exchange.NewSession(ctx)
+
 	dagNode, err := api.core().ResolveNode(ctx, p)
 	if err != nil {
 		return fmt.Errorf("pin: %s", err)
@@ -80,6 +84,8 @@ func (api *PinAPI) Rm(ctx context.Context, p path.Path, opts ...caopts.PinRmOpti
 }
 
 func (api *PinAPI) Update(ctx context.Context, from path.Path, to path.Path, opts ...caopts.PinUpdateOption) error {
+	ctx = exchange.NewSession(ctx)
+
 	settings, err := caopts.PinUpdateOptions(opts...)
 	if err != nil {
 		return err

core/corehttp/gateway_handler.go

@@ -16,6 +16,7 @@ import (
 
 	humanize "github.com/dustin/go-humanize"
 	"github.com/ipfs/go-cid"
+	exchange "github.com/ipfs/go-ipfs-exchange-interface"
 	files "github.com/ipfs/go-ipfs-files"
 	dag "github.com/ipfs/go-merkledag"
 	mfs "github.com/ipfs/go-mfs"
@@ -89,6 +90,11 @@ func (i *gatewayHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	// the hour is a hard fallback, we don't expect it to happen, but just in case
 	ctx, cancel := context.WithTimeout(r.Context(), time.Hour)
 	defer cancel()
+
+	// Always create a root session for http requests.
+	// That way we do all path resolution etc in the same session.
+	ctx = exchange.NewSession(ctx)
+
 	r = r.WithContext(ctx)
 
 	defer func() {

go.mod

@@ -14,7 +14,7 @@ require (
 	github.com/gogo/protobuf v1.3.1
 	github.com/hashicorp/go-multierror v1.1.0
 	github.com/hashicorp/golang-lru v0.5.4
-	github.com/ipfs/go-bitswap v0.2.11
+	github.com/ipfs/go-bitswap v0.2.12-0.20200423051144-fa8848292027
 	github.com/ipfs/go-block-format v0.0.2
 	github.com/ipfs/go-blockservice v0.1.3
 	github.com/ipfs/go-cid v0.0.5
@@ -33,7 +33,7 @@ require (
 	github.com/ipfs/go-ipfs-cmds v0.2.2
 	github.com/ipfs/go-ipfs-config v0.5.2
 	github.com/ipfs/go-ipfs-ds-help v0.1.1
-	github.com/ipfs/go-ipfs-exchange-interface v0.0.1
+	github.com/ipfs/go-ipfs-exchange-interface v0.0.2-0.20200423055703-2e8ddd22ab43
 	github.com/ipfs/go-ipfs-exchange-offline v0.0.1
 	github.com/ipfs/go-ipfs-files v0.0.8
 	github.com/ipfs/go-ipfs-pinner v0.0.4
@@ -46,7 +46,7 @@ require (
 	github.com/ipfs/go-ipld-git v0.0.3
 	github.com/ipfs/go-ipns v0.0.2
 	github.com/ipfs/go-log v1.0.4
-	github.com/ipfs/go-merkledag v0.3.1
+	github.com/ipfs/go-merkledag v0.3.2-0.20200423061109-59b2ffa4efde
 	github.com/ipfs/go-metrics-interface v0.0.1
 	github.com/ipfs/go-metrics-prometheus v0.0.2
 	github.com/ipfs/go-mfs v0.1.1
@@ -107,3 +107,7 @@ require (
 )
 
 go 1.13
+
+replace github.com/ipfs/go-bitswap => /home/steb/.local/share/go/src/github.com/ipfs/go-bitswap
+
+replace github.com/ipfs/go-merkledag => /home/steb/.local/share/go/src/github.com/ipfs/go-merkledag