daknuett/scientific-programming-exercises
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added mysql cache support

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This commit is contained in:
Daniel Knüttel 2019-02-19 14:16:22 +01:00
parent a933d441ce
commit 95649ace91
5 changed files with 70 additions and 35 deletions
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19
exam/ex01/cache.py
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@ -18,9 +18,10 @@ def get_cache(directory, name):
cursor = db.cursor()
cursor.execute("CREATE TABLE proxies(proxy TEXT, lasttime_could_not_be_used DECIMAL)")
cursor.execute("CREATE TABLE links(source TEXT, destination TEXT)")
cursor.execute("CREATE TABLE dijkstra_helper(name TEXT UNIQUE, value INT)")
cursor.execute("CREATE TABLE failed_to_fetch(title TEXT, depth INT)")
cursor.execute("CREATE TABLE links(source INT, destination INT)")
cursor.execute("CREATE TABLE dijkstra_helper(page INT UNIQUE, value INT)")
cursor.execute("CREATE TABLE failed_to_fetch(page INT, depth INT)")
cursor.execute("CREATE TABLE pages(title TEXT)")
db.commit()
db = sqlite3.connect(cache_file)
@ -36,9 +37,15 @@ def get_cache(directory, name):
cursor = db.cursor()
cursor.execute("CREATE TABLE IF NOT EXISTS proxies(proxy varchar(100), lasttime_could_not_be_used DECIMAL)")
cursor.execute("CREATE TABLE IF NOT EXISTS links(source varchar(100) CHARACTER SET utf8mb4, destination varchar(100) CHARACTER SET utf8mb4)")
cursor.execute("CREATE TABLE IF NOT EXISTS dijkstra_helper(name varchar(100) CHARACTER SET utf8mb4 UNIQUE, value INT)")
cursor.execute("CREATE TABLE IF NOT EXISTS failed_to_fetch(title varchar(100) CHARACTER SET utf8mb4, depth INT)")
cursor.execute("CREATE TABLE IF NOT EXISTS links(source INT, destination INT)")
cursor.execute("CREATE TABLE IF NOT EXISTS dijkstra_helper(page INT UNIQUE, value INT)")
cursor.execute("CREATE TABLE IF NOT EXISTS failed_to_fetch(page INT, depth INT)")
cursor.execute('''CREATE TABLE IF NOT EXISTS
pages(
title varchar(400) CHARACTER SET utf8mb4
, page_id INT AUTO_INCREMENT
, PRIMARY KEY(page_id)
)''')
db.commit()
fetch_proxies(db)

15
exam/ex01/connectivity.py
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@ -1,10 +1,12 @@
from collections import deque
from cfg import config
from db_util import get_page_id
def can_reach(title, connection):
page = get_page_id(title, connection)
cursor = connection.cursor()
cursor.execute("SELECT COUNT(destination) FROM links WHERE destination=%s", (title, ))
cursor.execute("SELECT COUNT(destination) FROM links WHERE destination=%s", (page, ))
count = cursor.fetchone()[0]
return count > 0
@ -13,16 +15,17 @@ def shortest_path(center, title, connection):
return []
cursor = connection.cursor()
current_title = title
current_page = get_page_id(title, connection)
center_page = get_page_id(center, connection)
path = deque()
while(current_title != center):
while(current_page != center_page):
path.append(current_title)
cursor.execute('''SELECT links.source
FROM links
LEFT JOIN dijkstra_helper ON links.destination=dijkstra_helper.name
WHERE links.destination=:title
LEFT JOIN dijkstra_helper ON links.destination=dijkstra_helper.page
WHERE links.destination=:page
ORDER BY dijkstra_helper.value ASC
LIMIT 1''', {"title": current_title})
LIMIT 1''', {"page": current_page})
current_title = cursor.fetchone()[0]
return list(reversed(path))

25
exam/ex01/dijkstra.py
View File

@ -1,12 +1,16 @@
from collections import deque
from cfg import config
from db_util import get_page_id
def prepare_dijkstra(connection):
cursor = connection.cursor()
cursor.execute('''INSERT OR IGNORE INTO dijkstra_helper(name)
cursor.execute('''INSERT OR IGNORE INTO dijkstra_helper(page)
SELECT destination FROM links
''')
cursor.execute('''INSERT OR IGNORE INTO dijkstra_helper(page)
SELECT source FROM links
''')
if(config["use_sqlite"]):
cursor.execute("UPDATE dijkstra_helper SET value=1e1000")
@ -14,16 +18,16 @@ def prepare_dijkstra(connection):
cursor.execute("UPDATE dijkstra_helper SET value=2147483647")
connection.commit()
def dijkstra_one(title, value, connection):
def dijkstra_one(page, value, connection):
cursor = connection.cursor()
if(isinstance(title, tuple)):
# Idk why this happens.
title = title[0]
cursor.execute('''SELECT name
cursor.execute('''SELECT page
FROM dijkstra_helper
LEFT JOIN links ON links.destination=dijkstra_helper.name
WHERE links.source=:title
AND dijkstra_helper.value>:value''', {"title": title, "value": value + 1})
LEFT JOIN links ON links.destination=dijkstra_helper.page
WHERE links.source=:page
AND dijkstra_helper.value>:value''', {"pate": page, "value": value + 1})
# This is the list of nodes that have to be updated
result = cursor.fetchall()
@ -32,8 +36,8 @@ def dijkstra_one(title, value, connection):
WHERE name IN (
SELECT destination
FROM links
WHERE source=:title)
AND dijkstra_helper.value>:value''', {"value": value + 1, "title": title})
WHERE source=:page)
AND dijkstra_helper.value>:value''', {"value": value + 1, "page": page})
connection.commit()
return result
@ -49,10 +53,11 @@ def recursive_dijkstra(titles, value, connection):
def dijkstra(title, connection):
page = get_page_id(title, connection)
cursor = connection.cursor()
cursor.execute("UPDATE dijkstra_helper SET value=0 WHERE name=%s", (title,))
cursor.execute("UPDATE dijkstra_helper SET value=0 WHERE name=%s", (page,))
todos = dijkstra_one(title, 1, connection)
todos = dijkstra_one(page, 1, connection)
recursive_dijkstra(todos, 2, connection)

10
exam/ex01/proxy.py
View File

@ -25,16 +25,20 @@ def get_data_with_proxy(url, conn_object, visit_first=None):
session.proxies = { 'http': i}
try:
response = session.get(url, headers=headers, timeout=3)
except:
except Exception as e:
if(isinstance(e, KeyboardInterrupt)):
raise e
# If proxy is invalid/inactive, update lasttime could not be used and go next proxy
cursor.execute('''UPDATE proxies SET lasttime_could_not_be_used = %d WHERE proxy = %s ''',
cursor.execute('''UPDATE proxies SET lasttime_could_not_be_used = %s WHERE proxy = %s ''',
(time.time(), i))
continue
# If text is empty, update lasttime could not be used and go next proxy
if not response.text or 399 < response.status_code < 600:
cursor.execute('''UPDATE proxies SET lasttime_could_not_be_used = %d WHERE proxy = %s ''',
cursor.execute('''UPDATE proxies SET lasttime_could_not_be_used = %s WHERE proxy = %s ''',
(time.time(), i))
continue
# Be nice to Wikipedia.
time.sleep(0.3)
return response.json()
raise NoMoreProxiesException("No more proxies left")

36
exam/ex01/receive.py
View File

@ -1,6 +1,7 @@
import logging
from url import construct_url
from proxy import get_data_with_proxy, NoMoreProxiesException
from db_util import get_page_id
logger = logging.getLogger(__name__)
@ -19,6 +20,8 @@ def ignore_title(title):
def _receive_links(title, connection):
url = construct_url(title)
source = get_page_id(title, connection)
result = get_data_with_proxy(url, connection)
# This is basically because we don't know the page ID.
for k, page_data in result["query"]["pages"].items():
@ -30,7 +33,8 @@ def _receive_links(title, connection):
continue
if(ignore_title(title)):
continue
cursor.execute("INSERT INTO links(source, destination) VALUES(%s, %s)", (title, destination_title))
destination = get_page_id(destination_title, connection)
cursor.execute("INSERT INTO links(source, destination) VALUES(%s, %s)", (source, destination))
yield destination_title
else:
@ -38,11 +42,8 @@ def _receive_links(title, connection):
if(ignore_title(title)):
continue
destination_title = destination["title"].replace(" ", "_")
try:
cursor.execute("INSERT INTO links(source, destination) VALUES(%s, %s)", (title, destination_title))
except Exception as e:
print(destination_title)
raise e
destination = get_page_id(destination_title, connection)
cursor.execute("INSERT INTO links(source, destination) VALUES(%s, %s)", (source, destination))
yield destination_title
connection.commit()
@ -50,14 +51,28 @@ def receive_links(title, connection):
return list(_receive_links(title, connection))
def receive_link_graph(title, connection, depth):
def receive_link_graph(title, connection, depth, fetch_missing=True):
cursor = connection.cursor()
# Fetch the missing links.
if(fetch_missing):
delete_cursor = connection.cursor()
cursor.execute('''SELECT pages.title, failed_to_fetch.depth, failed_to_fetch.page
FROM failed_to_fetch
LEFT JOIN pages ON pages.page_id=failed_to_fetch.page''')
for t, d, p in cursor:
receive_link_graph(t, connection, d, fetch_missing=False)
delete_cursor.execute("DELETE FROM failed_to_fetch WHERE page=%s", (p,))
if(depth < 0):
# end of recursion
return
page = get_page_id(title, connection)
cursor = connection.cursor()
print(repr(title))
cursor.execute("SELECT COUNT(source) FROM links WHERE source=%s", (title,))
cursor.execute("SELECT COUNT(source) FROM links WHERE source=%s", (page,))
if(cursor.fetchone()[0] != 0):
# we fetched that title already
return
@ -73,7 +88,8 @@ def receive_link_graph(title, connection, depth):
# Retry later, so we have to store our list that is still to fetch.
cursor = connection.cursor()
cursor.execute("INSERT INTO failed_to_fetch(title, depth) VALUES(%s, %d)", (link, depth - 1))
failed_page = get_page_id(link, connection)
cursor.execute("INSERT INTO failed_to_fetch(page, depth) VALUES(%s, %s)", (failed_page, depth - 1))
connection.commit()