Optimize Query insertMangaImage & Typo Fix

[jwshields]

Hello!

This PR is to change the insertMangaImage function which inserts images into the Manga table;
I have also fixed a typo in the dropDatabase function.

1. I have renamed the insertMangaImage function to insertMangaImages - this is to more closely align the name of the function with what it does with these changes.
2. I have changed a few lines in the process_image function; this is to improve speed and resource utilization while inserting manga into the DB, and to better form the data for the insertMangaImages function.
3. The dropDatabase function had a typo in it, I changed the query from DROP IF EXISTS TABLE -> DROP TABLE IF EXISTS (Docs: https://www.sqlite.org/lang_droptable.html)

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Explanation & Reasoning:

The previous method invoked the insertMangaImage function for each page in a manga; this can create a lot of overhead, in terms of the number of times variables are passed around, the number of times extra functions are invoked, and as well as opening/committing/closing a connection to the SQLite DB for each page.

The changes I have made reduce that to invoking the insertMangaImage(s) function once, opening and closing a single connection to the DB, and adding all needed rows to the DB in a batch operation-
This should result in a large increase in speed of inserting manga, but it largely depends on the number of pages in an image/artwork.
In my manual testing in the python console with dummy data, I've seen about a 3-5x increase in speed, but my testing may not be a direct parallel.

Please let me know if you think there are other changes needed here, or if you have feedback on these changes.

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Info:

import sqlite3
import timeit
tempdb = sqlite3.connect(":memory:")
cur = tempdb.cursor()
def redoTable():
    cur.execute('''DROP TABLE IF EXISTS temp_manga_table''')
    tempdb.commit()
    cur.execute('''CREATE TABLE temp_manga_table (image_id TEXT, save_name TEXT, page TEXT);''')
    tempdb.commit()
def genlist():
    templist = list()
    tempnum = 0
    while 150 > tempnum:
        tempitem = (f"aaa{tempnum}", f"aaa{tempnum}", f"aaa{tempnum}")
        templist.append(tempitem)
        tempnum += 1
    return templist
def insertone():
    templist = genlist()
    for item in templist:
        tempcur = tempdb.cursor()
        tempcur.execute('''INSERT OR IGNORE INTO temp_manga_table VALUES(?,?,?)''', item)
        tempdb.commit()
def insertmany():
    templist = genlist()
    tempcur = tempdb.cursor()
    tempcur.executemany('''INSERT OR IGNORE INTO temp_manga_table VALUES(?,?,?)''', templist)
    tempdb.commit()
def insertandcreateone():
    redoTable()
    insertone()
def insertandcreatemany():
    redoTable()
    insertmany()

timeit.timeit(insertandcreateone, number=50)
0.05511809999995876
timeit.timeit(insertandcreatemany, number=50)
0.019706499999983862

timeit.timeit(insertandcreateone, number=500)
0.5120501000000104
timeit.timeit(insertandcreateone, number=500)
0.5187395000000379
timeit.timeit(insertandcreatemany, number=500)
0.17566390000001775
timeit.timeit(insertandcreatemany, number=500)
0.18835190000004332

timeit.timeit(insertandcreateone, number=5000)
5.130790800000341
timeit.timeit(insertandcreatemany, number=5000)
1.776915800000097

timeit.timeit(insertandcreateone, number=50000)
52.0960113000001
timeit.timeit(insertandcreatemany, number=50000)
17.997701900000266