From 721b9d36af1e0f6f8236dd705c3e3301c46d84cc Mon Sep 17 00:00:00 2001
From: Max Hutchinson <maxhutch@gmail.com>
Date: Tue, 29 Sep 2015 13:06:19 -0500
Subject: [PATCH 1/4] Adding "readonly" option to constructor to avoid writes.

Read-only disables `__delitem__` and `__setitem__` and `__del__`
---
 chest/core.py            | 12 ++++++++++++
 chest/tests/test_core.py | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 47 insertions(+)

diff --git a/chest/core.py b/chest/core.py
index fa95d44..21b97c9 100644
--- a/chest/core.py
+++ b/chest/core.py
@@ -95,6 +95,7 @@ def __init__(self, data=None, path=None, available_memory=None,
                  on_miss=_do_nothing, on_overflow=_do_nothing,
                  open=open,
                  open_many=_open_many,
+                 readonly=False,
                  mode='b'):
         # In memory storage
         self.inmem = data or dict()
@@ -115,6 +116,9 @@ def __init__(self, data=None, path=None, available_memory=None,
         self.open = open
         self.open_many = open_many
         self._key_to_filename = key_to_filename
+        self.readonly = readonly
+        if (not self._explicitly_given_path) and self.readonly:
+            raise TypeError("Can't create an empty readonly chest")
 
         keyfile = os.path.join(self.path, '.keys')
         try:
@@ -196,6 +200,9 @@ def _update_lru(self, key):
         self.heap[key] = self.counter
 
     def __delitem__(self, key):
+        if self.readonly:
+            raise TypeError("Can't delete from readonly chest")
+
         if key in self.inmem:
             self.memory_usage -= nbytes(self.inmem[key])
             del self.inmem[key]
@@ -209,6 +216,9 @@ def __delitem__(self, key):
         del self._keys[key]
 
     def __setitem__(self, key, value):
+        if self.readonly:
+            raise TypeError("Can't assign in readonly chest")
+
         with self.lock:
             if key in self._keys:
                 del self[key]
@@ -222,6 +232,8 @@ def __setitem__(self, key, value):
             self.shrink()
 
     def __del__(self):
+        if self.readonly:
+            return
         if self._explicitly_given_path:
             if os.path.exists(self.path):
                 self.flush()
diff --git a/chest/tests/test_core.py b/chest/tests/test_core.py
index 544a6fb..647b9b9 100644
--- a/chest/tests/test_core.py
+++ b/chest/tests/test_core.py
@@ -458,3 +458,38 @@ def test_prefetch():
         assert not raises(KeyError, lambda: c[1])
         c.prefetch([1, 2])
         assert not raises(KeyError, lambda: c[2])
+
+
+def test_readonly():
+    with tmp_chest(path="here") as c1:
+        c1[0] = 0
+        c1["foo"] = "bar"
+        c1.flush()
+        with tmp_chest(path="here", readonly=True) as c2:
+            assert c2[0] == 0
+            assert c2["foo"] == "bar"
+            try:
+                c2[0] = 1
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+            try:
+                c2["spam"] = "eggs"
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+            try:
+                del c2["foo"]
+                assert False
+            except TypeError:
+                assert True
+            except:
+                assert False
+
+
+def test_readonly_nopath():
+    assert raises(TypeError, lambda: Chest(readonly=True))

From e435e66b54e391c83ffdf7196dc801f8ec93ed15 Mon Sep 17 00:00:00 2001
From: Max Hutchinson <maxhutch@gmail.com>
Date: Tue, 29 Sep 2015 13:14:12 -0500
Subject: [PATCH 2/4] Be sure to delete the in-memory data.

---
 chest/core.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/chest/core.py b/chest/core.py
index 21b97c9..a1d5b77 100644
--- a/chest/core.py
+++ b/chest/core.py
@@ -117,8 +117,6 @@ def __init__(self, data=None, path=None, available_memory=None,
         self.open_many = open_many
         self._key_to_filename = key_to_filename
         self.readonly = readonly
-        if (not self._explicitly_given_path) and self.readonly:
-            raise TypeError("Can't create an empty readonly chest")
 
         keyfile = os.path.join(self.path, '.keys')
         try:
@@ -138,6 +136,9 @@ def __init__(self, data=None, path=None, available_memory=None,
         self._on_miss = on_miss
         self._on_overflow = on_overflow
 
+        if (not self._explicitly_given_path) and self.readonly:
+            raise TypeError("Can't create an empty readonly chest")
+
     def __str__(self):
         return '<chest at %s>' % self.path
 
@@ -232,10 +233,8 @@ def __setitem__(self, key, value):
             self.shrink()
 
     def __del__(self):
-        if self.readonly:
-            return
         if self._explicitly_given_path:
-            if os.path.exists(self.path):
+            if os.path.exists(self.path) and not self.readonly:
                 self.flush()
             else:
                 with self.lock:

From 62f7f74bed7c55a18c66fa92249e896e4ba850be Mon Sep 17 00:00:00 2001
From: Max Hutchinson <maxhutch@gmail.com>
Date: Tue, 29 Sep 2015 13:19:40 -0500
Subject: [PATCH 3/4] Coverage no longer supports python 3.2, but let's add 3.5

---
 .travis.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index c4e371c..6ebfbd6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,9 +2,9 @@ language: python
 python:
     - "2.6"
     - "2.7"
-    - "3.2"
     - "3.3"
     - "3.4"
+    - "3.5"
 
 env:
     - PEP8_IGNORE=""

From 42930168674c230d7d14108a118caa39a295eef2 Mon Sep 17 00:00:00 2001
From: Max Hutchinson <maxhutch@gmail.com>
Date: Tue, 29 Sep 2015 13:22:14 -0500
Subject: [PATCH 4/4] Maybe too soon for 3.5

---
 .travis.yml | 1 -
 1 file changed, 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 6ebfbd6..443574e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,6 @@ python:
     - "2.7"
     - "3.3"
     - "3.4"
-    - "3.5"
 
 env:
     - PEP8_IGNORE=""