Add hash-backend and update README.

1 files changed, 19 insertions, 10 deletions

diff --git a/src/eris-decode.lisp b/src/eris-decode.lisp
index ba20e9d..3d93312 100644
--- a/src/eris-decode.lisp
+++ b/src/eris-decode.lisp
@@ -218,19 +218,28 @@ hash-table is used, a (copy-seq) needs to be done on the return value of
 gethash.
 
 The keyword argument CACHE-CAPACITY indicates the amount of blocks stored in the
-cache."
+cache. It may be NIL to turn off caching entirely."
   (declare (type read-capability read-capability)
            (type function fetch-function)
-           (type integer cache-capacity))
+           (type (or integer null) cache-capacity))
   (with-slots (level block-size root-reference-pair) read-capability
-    (let* ((get-block (cached-lambda (:cache-class 'lru-cache 
-                                      :capacity cache-capacity
-                                      :table (make-hash-table :size (1+ cache-capacity) :test #'equalp))
-                          (reference key &optional nonce)
-                        (let* ((block (execute-fetch-function fetch-function reference)))
-                          (unless block (error 'missing-block :reference reference))
-                          (hash-check block reference)
-                          (decrypt-block block key nonce))))
+    (let* ((get-block (if cache-capacity ;; handle caching
+                          (cached-lambda (:cache-class 'lru-cache 
+                                                       :capacity cache-capacity
+                                                       :table (make-hash-table :size (1+ cache-capacity) :test #'equalp))
+                                         (reference key nonce)
+                                         (declare (type octet-vector reference key))
+                                         (let ((block (execute-fetch-function fetch-function reference)))
+                                           (declare (type octet-vector block))
+                                           (hash-check block reference)
+                                           (decrypt-block block key nonce)))
+                        (lambda (reference key nonce)
+                          (declare (type octet-vector reference key)
+                                   (optimize (debug 3)))
+                          (let ((block (execute-fetch-function fetch-function reference)))
+                            (declare (type octet-vector block))
+                            (hash-check block reference)
+                            (decrypt-block block key nonce)))))
            (root (funcall get-block (reference root-reference-pair) (key root-reference-pair) (make-nonce level))))
       ;; "Implementations MUST verify the key appearing in the read capability
       ;; if level of encoded content is larger than 0."