More buildout of the Bitswap protocol

cid/cid.c

@@ -251,6 +251,10 @@ int ipfs_cid_cast(const unsigned char* incoming, size_t incoming_size, struct Ci
 
 /**
  * Compare two cids
+ *
+ * TODO: find a common denominator between versions and codecs so that
+ * we can compare apples to apples.
+ *
  * @param a side A
  * @param b side B
  * @returns < 0 if side A is greater, > 0 if side B is greater, or 0 if equal

exchange/bitswap/Makefile

@@ -7,7 +7,7 @@ endif
 
 LFLAGS = 
 DEPS = 
-OBJS = bitswap.o message.o network.o peer_request_queue.o
+OBJS = bitswap.o message.o network.o peer_request_queue.o want_manager.o
 
 %.o: %.c $(DEPS)
 	$(CC) -c -o $@ $< $(CFLAGS)

exchange/bitswap/bitswap.c

@@ -2,10 +2,12 @@
  * Methods for the Bitswap exchange
  */
 #include <stdlib.h>
+#include <unistd.h> // for sleep()
 #include "ipfs/core/ipfs_node.h"
 #include "ipfs/exchange/exchange.h"
 #include "ipfs/exchange/bitswap/bitswap.h"
 #include "ipfs/exchange/bitswap/message.h"
+#include "ipfs/exchange/bitswap/want_manager.h"
 
 /**
  * Create a new bitswap exchange
@@ -89,6 +91,10 @@ int ipfs_bitswap_has_block(void* exchangeContext, struct Block* block) {
  * Implements the Exchange->GetBlock method
  * We're asking for this method to get the block from peers. Perhaps this should be
  * taking in a pointer to a callback, as this could take a while (or fail).
+ * @param exchangeContext a BitswapContext
+ * @param cid the Cid to look for
+ * @param block a pointer to where to put the result
+ * @returns true(1) if found, false(0) if not
  */
 int ipfs_bitswap_get_block(void* exchangeContext, struct Cid* cid, struct Block** block) {
 	struct BitswapContext* bitswapContext = (struct BitswapContext*)exchangeContext;
@@ -97,6 +103,30 @@ int ipfs_bitswap_get_block(void* exchangeContext, struct Cid* cid, struct Block*
 		if (bitswapContext->ipfsNode->blockstore->Get(bitswapContext->ipfsNode->blockstore->blockstoreContext, cid, block))
 			return 1;
 		// now ask the network
+		//NOTE: this timeout should be configurable
+		int timeout = 10;
+		int waitSecs = 1;
+		int timeTaken = 0;
+		if (ipfs_bitswap_want_manager_add(bitswapContext, cid)) {
+			// loop waiting for it to fill
+			while(1) {
+				if (ipfs_bitswap_want_manager_received(bitswapContext, cid)) {
+					if (ipfs_bitswap_want_manager_get_block(bitswapContext, cid, block)) {
+						// NOTE: this should use reference counting
+						ipfs_bitswap_want_manager_remove(bitswapContext, cid);
+						return 1;
+					}
+				}
+				//TODO: This is a busy-loop. Find another way.
+				timeTaken += waitSecs;
+				if (timeTaken >= timeout) {
+					// It took too long. Stop looking.
+					ipfs_bitswap_want_manager_remove(bitswapContext, cid);
+					break;
+				}
+				sleep(waitSecs);
+			}
+		}
 	}
 	return 0;
 }

exchange/bitswap/want_manager.c

@@ -0,0 +1,52 @@
+#include "ipfs/exchange/bitswap/want_manager.h"
+#include "ipfs/exchange/bitswap/wantlist.h"
+
+/***
+ * Add a Cid to the local wantlist
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) on success, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_add(const struct BitswapContext* context, const struct Cid* cid) {
+	// first see if it is already here
+	// increment the reference count
+	return 0;
+}
+
+/***
+ * Checks to see if the requested block has been received
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) if it has been received, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_received(const struct BitswapContext* context, const struct Cid* cid) {
+	// find the entry
+	// check the status
+	return 0;
+}
+
+/***
+ * retrieve a block from the WantManager. NOTE: a call to want_manager_received should be done first
+ * @param context the context
+ * @param cid the Cid to get
+ * @param block a pointer to the block that will be allocated
+ * @returns true(1) on success, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_get_block(const struct BitswapContext* context, const struct Cid* cid, struct Block** block) {
+	// find the entry
+	// return a copy of the block
+	return 0;
+}
+
+/***
+ * We no longer are requesting this block, so remove it from the queue
+ * NOTE: This is reference counted, as another process may have asked for it.
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) on success, false(0) otherwise.
+ */
+int ipfs_bitswap_want_manager_remove(const struct BitswapContext* context, const struct Cid* cid) {
+	// decrement the reference count
+	// if it is zero, remove the entry (lock first)
+	return 0;
+}

include/ipfs/exchange/bitswap/bitswap.h

@@ -1,3 +1,5 @@
+#pragma once
+
 /***
  * Bitswap implements the exchange "interface"
  * @see ../exchange.h
@@ -9,6 +11,7 @@
 struct BitswapContext {
 	struct SessionContext* sessionContext;
 	struct IpfsNode* ipfsNode;
+	struct Wantlist* localWantlist;
 };
 
 /**

include/ipfs/exchange/bitswap/want_manager.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include "ipfs/blocks/block.h"
+#include "ipfs/cid/cid.h"
+#include "ipfs/exchange/bitswap/bitswap.h"
+
+/***
+ * Add a Cid to the local wantlist
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) on success, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_add(const struct BitswapContext* context, const struct Cid* cid);
+
+/***
+ * Checks to see if the requested block has been received
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) if it has been received, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_received(const struct BitswapContext* context, const struct Cid* cid);
+
+/***
+ * retrieve a block from the WantManager. NOTE: a call to want_manager_received should be done first
+ * @param context the context
+ * @param cid the Cid to get
+ * @param block a pointer to the block that will be allocated
+ * @returns true(1) on success, false(0) otherwise
+ */
+int ipfs_bitswap_want_manager_get_block(const struct BitswapContext* context, const struct Cid* cid, struct Block** block);
+
+/***
+ * We no longer are requesting this block, so remove it from the queue
+ * NOTE: This is reference counted, as another process may have asked for it.
+ * @param context the context
+ * @param cid the Cid
+ * @returns true(1) on success, false(0) otherwise.
+ */
+int ipfs_bitswap_want_manager_remove(const struct BitswapContext* context, const struct Cid* cid);